A MONOGRAPH ON THE FOSSIL LEPADIDAE, DARWIN 1851

A MONOGRAPH ON THE FOSSIL LEPADID^E, OK, PEDUNCULATED CffiRIPEDES OE GREAT BRITAIN BY CHARLES DARWIN, F.R.S., F.G.S ZA-ZZSq LONDON: PRINTED FOR THE PALM)NTOGRAPHICAL SOCIETY 1851 C AND J ADLARD, PRINTERS, BARTHOLOMEW CLOSE PREFACE have I great pleasure in returning me both for intrusting to whenever it stranger to was of the gentlemen to labour whom my me To Mr freest Mr Wetherell placed in specimen of Loricula pulchetta, and other species own as known, discovered and named by him Woodward, Tennant, and F Edwards, Harris, S of several species new to kind manner, supplied specimens rendered to and Fitch, — me me me by Although an entire of Norwich, I here beg- use of his my hands Professor fine his beautiful Buckman much Searles Wood, owe the examination valuable information, and with the loan of my C Sowerby I must express for the pains exhibited in the many thanks for the valuable aid ' Mineral Conchology;' drawings here published specimens deposited in the Geological Museum my disposal many me the collection in the Zoological department, including the highly valuable original specimens of his excellent Denmark and second large collection, the Scania fruit valuable of the University, but applied to Professor Steenstrup, who, in the most generous manner, sent a and unique most ancient Cirripede other gentlemen, I Professor Forchhammer, of Copenhagen, not only placed at me in sent me, of his To Messrs Flower, the loan of the original specimens figured in the the Fossil Cirripedia of rich collection, Mr Morris and Professor E Forbes have, in their usual with To Mr James de me, the fruit of twenty years' accord, a fine series of the valves of Pollicipes oolitims, the yet allowing during several months, his unrivalled to keep, the for naturalists, have in every instance received Upper Chalk of Norwich, Mr Bowerbank has given specimens from the Gault me and their matrix I applied, I demands thanks, for having allowed of Cirripedia from the collection from advisable, to clear the specimens many my most sincere thanks to various their collections of Fossil Cirripedia, the most courteous acquiescence to to return my Memoir on Subsequently, Professor Steenstrup sent of the indefatigable labours of M Angelin, in PREFACE vi Scania : all these northern specimens have been of the greatest use to Having applied the' British species species described his own of great value sincere thanks W Dunker, of Cassel, and to these Lastly, I who most distinguished may be for many months collections of recent Cirripedia, here only state, that of the British the Cirripedia, for some of the of but procured from Messrs Roemer, Koch, and Philippi, other specimens permitted to naturalists I state, it and who have was owing Museum, that I together have left in assisted to the suggestion was first beg to return my that I hope very soon another and more appropriate opportunity of publicly expressing gentlemen, in illustrating by various German authors, he not only sent me many specimens out collection, ; to Professor me my my very to have gratitude to various hands their large and valuable me in every possible way and encouragement of Mr I will J E Gray, induced to take up the systematic description of having originally intended only to study their anatomy foregoing gentlemen, I shall ever feel under the deepest obligations To all the INTRODUCTION The Cirripedia, both naturalists and recent the fossil species have, however, been : Professor Steenstrup has published Cretaceous species Mr : more attended and F Roemer has ; As have appeared by several authors Cirripedia and ; yet, The present volume so it to than the recent an excellent monograph on the Danish and Scanian illustrated, though clear descriptions, various German forms on the whole group neglected by systematic de Carle Sowerby has given good plates of several British J valves in the Mineral Conchology figures, much have been fossil, Other by rather less indifferent important notices however, no monograph has been produced is confined to the Lepadidce or Pedunculated happens that the introduction, under the form of notes, of a few foreign species (which are necessary to illustrate the British species), serves to render Monograph this tolerably complete ; that is, as far as the specimens collected Continent (judging from published accounts) serve for this end, — we on the shall immediately species have been found for see that certain valves are requisite in each genus It is unfortunate coembedded rarely all the valves of the evident that, with the exception of is it ; how which held the valves together, decayed very Hence, in the great majority of Cirripedes separate Hitherto it the valves all different kinds of valve, there many names in several instances, that ; and as in each characteristic valves, it species, the membrane does in recent Pedunculated the several valves have been found specific from three to species there are names five or six would have been, had not the whole group been much attached to each species many On the other hand, it has occurred valves belonging to quite different species have been grouped together under the same name most as some few been the practice of naturalists to attach has indifferently to neglected, so easily, cases, same To avoid these great evils, I have fixed on the one in each of the two main genera, and taking them as Naturhistorisk Tidsskrift, af H Kroyer, 1837 and 1839 Die Versteinerungen des Norddeutschen Kreidegebirges, 1841 ; ' FOSSIL CIRRIPEDIA to the known have never, except in one instance where several valves were typical, same individual, attached a specific all to belong and in another instance in which a valve was very remarkable, name to any other one I have, however, in two cases retained names already given to certain other valves, as they presented remarkable characters, and were almost certainly distinct In Scalpellum I have taken the Carina or Keel-valve valve of most authors) as typical most authors) valves of both genera but ; and in Pollicipes, the Scuta than any other valve in Scalpellum, in which genus in Pollicipes, it upper or posterior in most In almost collections lateral valves) all and are not characteristic, from the conditions of embedment, attributed to the Much same whereas e the are particularly liable to specific valves can other of the several (i often names, yet be safely confusion in nomenclature will, I think, be avoided by the plan here adopted seen in some species, ever fossil species, remain difficult have passed through my and to the variability of the valves, as from what so commonly occurs with recent as inferred In very owing I fear, many of those recent species, of have ranked them as quite distinct for instance, of Lesson — which discriminating series some series, I and again Pollicipes cornucopia, and elegans species of Zepas, which would be hopeless to attempt- it without quite perfect specimens fossilized, should unhesitatingly on the other hand there are some recent' species-, are perfectly distinct, but when which large hands, several of the valves have varied so much, that had I seen only certain specimens from the opposite poles of the — ; collected species but the study of Possil Cirripedia must, forms same valve in the Lepadidae the Terga Although only certain valves in each genus thus receive variation the inferior lateral highly characteristic is it dorsal present less striking characters than the Scuta, which are, apt to is commoner moreover, (i e desirable to have taken the happened that the Carina has been much more frequently so it ; would have been it : (i e should be borne in It mind, that the recognition of the Fossil Pedunculated Cirripedes by the whole of their valves and peduncle, is identical with recognising the organs of sense, the mouth, the legs, or valve is equivalent to doing this in a Crustacean carapace, without the great advantage of body of the included animal's : knowing adds one more to the : to by a by name single its carapace, without a Cirripede by a single definite portion of the its having received the impress of the viscera this, and yet often having the power to identify with ease and certainty a Cirripede by one of valve, a Crustacean abdomen many known its valves, or even by a fragment of a proofs of the exhaustless fertility of Nature in the production of diversified yet constant forms I must a]lude to one more unfortunate cause of doubt in the classification of the extinct Lepadidae, namely, the difficulty in attributing the separated valves to the main genera of Scalpellum and close genera in the recent be ascertained in fossil Pollicipes state, lies in specimens number the At for the chief distinction ; first have united both genera under Pollicipes ; of the valves, I determined to and two between these two this can very rarely follow those authors who but reflecting that I had twelve recent and ; ; INTRODUCTION above thirty-seven fossil many more being very There are Four of seemed discovered, this plan them have been unnamed other with almost the certainty species, six recent species species which me to — as have certainly equal, shall presently see — of too inconvenient to be followed work, to include under Scalpellum I intend, in a future by Dr Leach and Mr Gray raised we to the rank of genera • two not stronger, claims to the same rank if so again the six recent species of Pollicipes have similar claims to be divided into three thus making genera, genera for the twelve nine In the majority of cases Pollicipes species in these nine genera generic divisions of all ; recent would be eminently it species difficult to allocate mere invariably bound the other recent Pedunculated Cirripedes, there can be no doubt classificatory utility as make to making respect to me appears to ; I know not this particular case, if into six genera, they assuredly appears to how —genera me is if if we value would not be we As though eminently : with desirable, slight differences more raised the six recent species of Scalpellum distinct to an exactly equal degree and kept Scalpellum and easy to be recognised in a recent state, both genera were united into one, and are clear that the institution of so highly disadvantageous this, — which renders the of the fossil species, though always difficult and liable to than are allowed same weigh the value of to these circumstances I have followed a middle term, distinct, we or whether a difference in the maxillae or mandibles be the ; anyhow, in : it species are discovered, genera of exactly equal value, almost hopeless in different valves important all if as possible all genera of exactly the as far many more genera, until is, an element in the decision, and further, far as utility in classification is concerned, many the fossil nevertheless, taking the characters necessarily used for the that the formation of the above nine genera might be justified, that to neglect Scalpellum and of much many errors, easier than if the Under Pollicipes classification somewhat easier above nine genera were admitted Aptychus Before passing to more general considerations, I must offer a few remarks on the genus Aptychus, or Triyonellites, inasmuch as quite lately a distinguished naturalist, M D'Orbigny, has adopted, and with much anomalous bodies are Pedunculated Cirripedia and lines of or Anatifa : growth ingenuity supported, the view that these It cannot be denied that the general form closely resemble those of the Scuta or lateral inferior valves in nor can it be denied, from what we know of recent (upper lateral valves) and Carina (dorsal valve), which on species, that the it Terga M D'Orbigny's view must be considered as absent, are the most likely valves to disappear from abortion are points of difference which, as Lepas But there appears to me, are of far greater importance than the Cours Elementaire de Palecmtologie, 1849, vol i, p 254 FOSSIL CIRRIPEDIA The resemblance in mere outline peculiar cancellated structure, which the external surface even to the naked eye, Cirripedia is is almost visible on wholly unlike anything known amongst a thin polished slice of the valves of Lepas ; power, are as unlike as anything can well be and of Aptychus, viewed under a high In Aptychus the lines of growth are conspicuous on the inner or concave surface, and indistinguishable or not plain on the outer surface specimens ; Lepas exactly the reverse holds good whereas in made appears, that additions are it growing margin, instead of on the inner edge, there is cirri are supposed to have been protruded, and exactly or nearly so, In Aptychus latus, In anything which I have met this is unlike much the species of Aptychus, the two valves are all by the two margins through which the the most commonest case, or cover each other, for there when held must have been protruded cirri found either separate, which in all true fossil pedunculated Cirripedes, the valves are the edge of the exterior though not invariably, found widely opened, and attached together, either frequently, is Cirripedia in as some in a rather deep internal fold along the whole of that margin, through which the with in Cirripedes Now on the to the shell Again, on the opposite sides almost exactly together, those nothing in the structure of Cirripedia tending to open the is How valves like the ligament in bivalve shells comes then, that the specimens of it, Aptychus, even those found within the protected chambers of Ammonites, thus generally have their valves widely gaping ? Even we if pass over this difficulty, that the valves should always have been held together condition is by that margin, which supposed to have been open for a considerable portion of exsertion of the cirri ; its not strange in the recent length, for the whereas, in not one single instance, as far as I have seen, are the two valves held together by the opposite margin, which idea of Aptychus is it in the recent having been a Cirripede, must have been on the state, by continuously united membrane There is another argument against Aptychus having been a Cirripede, which will have weight, perhaps, with only a few persons is downwards ; in Lepas or Anatifa, as well as in most of the growth of the Scuta and of the Carina reversed direction, or upwards directly e (*" known Now to know ; whereas in is of only dorsal, or valves,) is in a the oldest two cretaceous grow both upwards and downwards relation between the age of I had the slices fossil made, I in main allied genera, the known genus of not is So again species in which which the Carina has this the recent and one Miocene species, these valves usually When Pollicipes and grow upwards and downwards, and only one case double direction of growth lateral, the valves have been discovered even in the newest Tertiary formation within the limits of the genus Scalpellum, I the Scuta lower all having been found in the Lower Oolite, whereas hitherto Lepas Cirripedes, certainly main growth of in Pollicipes, the : Hence it would appear that there is some Lepadidae and the upward or downward direction of did not know Acad Caes Leop Car.,' vol xv, Oct 1829, tab of H von Meyer's paper on Aptychus, in the 'Acta lviii are given of the microscopical structure of Aptychus and lix, Icevis fig 13, in which perfectly accurate sections INTRODUCTION the lines of growth in their valves M D'Orbigny, the oldest known its existed during the Aptychus, according to Carboniferous system, at a period vastly anterior to the idea of having been a Cirripede, the growth of upwards, as in the most recent forms and ; it was Pollicipes, yet valves (Scuta) its genus which, allied to Lepas, that on must have been in the order of creation, and in the manner of growth, stands at the opposite end of the series from Prom Pollicipes several reasons the Aptychus, until weightier evidence Geological History Secondary formation ; — No Sessile many does not appear to Cirripede has many species (to whom I am of his beautiful collection of recent species,) has assured much me These Cirripedes now abound information, that vast numbers and that he has carefully looked Sessile Cirripedes corals found in Eocene deposits, and subsequently, often in abundance, Tertiary Formations when of considerable value is deeply indebted for without success for those genera which commonly inhabit living first any are attached to are not likely to be overlooked and that they of fossil secondary corals have passed through his hands, are that hitherto been found in seems one of the cases in which negative evidence Mr Samuel Stutchbury, moreover, me others live in deep water in congregated masses, that their shells are not subject to decay, and the loan it considering that at the present time oceanic floating objects, that fossilized, this given, adduced, can be safely admitted as a Cirripede is true now so under every zone, in the all later over the world, that the present period will hereafter apparently have as good a claim to be called the age of Cirripedes, as the Palaeozoic period has to be called the age of Trilobites is one apparent exception to the rule that Sessile Cirripedes are not found in Secondary formations, for I a Verruca (== am enabled to announce that Mr Clisia, Clytia, Creusia, though hitherto included amongst the is There J de C Sowerby has in his collection Ochthosia) from our English chalk Sessile Cirripedes, must, when its : but this genus, whole organisation taken into consideration, be ranked in a distinct family of equal value with the Balanidse and Lepadidae, but perhaps more nearly Hence the presence related to the latter than to the Sessile Cirripedes of Verruca in the Chalk is Cirripedes not occur in Secondary formations law, that there on is some relation between no ; real exception to the rule that Sessile on the contrary, serial affinities of animals, it harmonises with the and their first appearance this earth The oldest Buckman known pedunculated Cirripede in the Stonesfield Slate in the is Lower a Pollicipes, Oolite : two discovered species of the by Professor same genus have been described by Mr Morris from the Oxford Clay, in the middle Oolite I have Dr Petzholdt has described and figured (Jahrbuch, 1842, p 403, tab x), a Balanus carbonaria from the carboniferous system the valves, nor their insufficient to ; but as neither tbe operculum, the structure of the manner of growth, can be made out admit the existence of this genus at so immensely a remote epoch Palaeontologicus,' gives, under Tubicinella, a cretaceous species consult the original work cited shell, the number of or are described, the evidence appears quite ; I Bronn, in the ' Index have unfortunately not been able to FOSSIL CIRRIPEDIA not heard of any Cirripede having been as yet discovered in the Upper Oolite, or in the Wealden formation During the deposition of the great Cretaceous System, the Lepadidas arrived at their culminant point some occurring species, known in every stage of this be discovered for examination, species ; in the ; from Upper Chalk five to eight in the all new I have three species Lower Chalk, and from nine to including the Faxoe, Scanian, and Maastricht (not to twelve species, five have namely near Norwich in one locality, many more that in almost every collection lent to fact, although very small, I have found some and of these nine or ten species, from the I infer this ; or four species from the Gault twelve stage) Besides the thirty-two certainly system cretaceous forms, and several other doubtful ones, I believe that very will yet me there were then three genera, and at least thirty-two ; been found by one M Angelin In Scania Mr Fitch, collector, has found no less than nine These belonging to the upper or Maastricht stage of the Chalk fossils, judging from the habits of recent species of the same genera, were probably attached to bottom of the fixed, or nearly fixed, objects at the sea Now at Pedunculata (reckoning even Crustacea andEchinidge as fixed ranean and New Alepas, which Zealand can boast each only of three imperfectly calcified valves as and a Lithotrya which have nine or ten we may admit species, in species, including whole Mediter- both cases including likely to be fossilized; one with very small and the great Phillipine Archipelago, however, has afforded, owing Mr Cuming, to the labours of valves, Madeira has four ; ; objects), the and therefore not destitute of calcified valves is Australia has three species the present day, of attached many lives species, embedded on from one fossil species as five locality, though including one with horny we Therefore since the beach already and from the same stage of the chalk, that the pedunculated Cirripedes arrived during the upper part of the Cretaceous system at their culminant point Although, for this family, the number of species were considerable during the Cretaceous period, the individuals were mostly rare in all collections in the chalk near ; Mr for instance, I infer this Fitch, who from the small number of specimens has assiduously collected for twenty years Norwich, possesses in his entire collection only nine keel-valves of Scal- pellum maximum, and six of S.fossula; he has two Scuta (and with regard to these valves, it must be remembered, that each individual had two) of Pollicipes P.fallax, and four of P Angelini region, between the number appertaining to such species, This occasional want of a of the species in any given genus, is a singular fact, naturally have expected, that where southern two of same and of the individuals and has been strongly Hooker, in regard to the Coniferous trees of the striatus, relation, within the on by Dr insisted hemisphere: one would circumstances favoured the existence of numerous species of a genus, they would likewise have favoured the multiplication of the indi- viduals in all or most of such species ; but this, as we here see, has not always been the case In the Eocene, Miocene, and Pliocene Tertiary deposits, I know only of two species of Scalpellum, and two of Pollicipes, with indications of two or three other species, all distinct CORONULA 39 This species, though closely allied to C diadema and easily confounded with no doubt original is distinct owe I specimen figured by Parkinson and more perfect specimen similar much worn but have been too ; and probably Mr Stutchbury's in collected from diadema, C —The tial The following description is to by which the present are of specific value longitudinal ribs on each compartment (i e the circumferen- transverse loops), are convex and prominent, as in C diadema, but they are crossed by more prominent ridges of growth 8a, 8e) than even in the roughest varieties of that (fig species, so that the surface of the shell is C a is one of which was young; as these specimens agree to four individuals, Structure of Shell collection there by Mr Searles Wood, belonging certainly in all essential respects, I feel pretty confident that the characters, species differ have both of these resemble C diadema in general form, to be positively identified drawn up from some compartments three and ; I it, Rev Mr Image an examination of the to the kindness of the diadema, and balcenaris, cupied by the whale's skin, outer portion, or that (fig more rugged regince, the surface of striated only is 8c/) by very In the three recent species the wall round the all fine longitudinal lines formed by the transverse loops, — viz., cavities oc- but here, the ; crossed by transverse is ridges of growth, like, but less prominent, than those on the external surface of the shell The minute regular, and can hardly be said be more strictly called other there size), ; for the is specimen — namely, (fig 8d, are about as thick as, is variable, in the same manner a peculiarity, which probably accidental, have seen in no I that one of the transverse circumferential loops at the end of one added folds The and therefore may be seen to, one of the cavities figure) to terminate in sutural edges the of or rather thicker than, in C compound diadema; for radii fig (d, (as in C balcenaris, 8b, 8c) of the as in C ; but in diadema and and each ala here regince, in all other Balanidse) of the radius, C barbara, instead of there by solid shell and although its Although the extent depth varies a little which sutural edges have margins of the whole ala is not alas it is to which The a central ridge, sending off are not short wedge-formed (fig but on a special plate this chamber in C diadema, yet there is a least filled up alse and is is filled marked most up (c, fig their up almost varies a difference filled little, between up, and those of are thick, as in C diadema, on both compared with 8c); not on the internal surface plate, this part is filled the specimens of this latter species, in which the chamber C barbara, in In the being a deep chamber, running up to the apex compartment, between the radius and the special entirely rests, 8b) middle part in the they not reach to the sheath by about half the thickness of the compartment same manner as In the rostrum which has been figured (86, enlarged twice on the right hand of the middle of the between two adjoining than teeth The exact number of the 8