Memoirs MCZ 2603

Umoirs of ilje Museum of Comnaratibe Zoology AT HARVARD COLLEGE Vol XXVI No REPORTS ON THE SCIENTIFIC RESULTS OF THE EXPEDITION TO THE TROPICAL PACIFIC, IN CHARGE OF ALEXANDER AGASSIZ, BY THE U S FISH COMMISSION STEAMER " ALBATROSS," FROM AUGUST, 1899, TO MARCH, 1900, COMMANDER JEFFERSON F MOSER, U S N., COMMANDING III MEDUSA BY ALEXANDER AGASSIZ and ALFRED GOLDSBOROUGH MAYER WITH THIRTEEN PLATES, AND A CHART OF THE ROUTE [Published by permission of Gbouge M Bowbhs, U S Commissioner of Fish aud Fisheries.] CAMBRIDGE, $rintcb for tfje U S A : IHusntm January, 1902 Reports on the Scientific Results of the Expedition to the Tropical Pacific in charge of Alexander Agassiz by the U S Fish Commission Steamer "Albatross," from August, 1899, to March, 1900, Commander Jefferson F Moser, U S N., commanding III MEDUSA By ALEXANDER AGASSIZ AND ALFRED GOLDSBOROUGH MAYER (Published by permission of Geo M Bowers, U S Commissioner o£ fish and Fisheries.) INTRODUCTION The medusae described in the following paper were obtained in thirty- four surface hauls, and in one bottom trawl made at 830 fathoms in the In addition to these there were thirteen intermediate hauls with Marquesas an open net, one at 100 fathoms, five at 150 fathoms, and seven between 250-350 fathoms and the The hauls in surface which medusae were captured were distributed Between San Francisco, Cal., and the Marquesas Among the Marquesas, Paumotus, and Society Islands Total as follows: — EXPEDITION OF THE "ALBATROSS," 140 1899-1900 region of the Japan current north of the Ladrones the water teemed with life, and the display fact it is phosphorescence at night was truly remarkable of In evident that pelagic animals are not abundant in regions far from large land masses or where there are no well defined oceanic currents or As soon counter currents as one approaches the region of great currents or counter currents, or the coasts of continents and larger islands, the number of animals increases with remarkable suddenness was very noticeable that during the daylight hours our surface tows It were generally deficient in animal while those life, made at the same time with an open net at depths varying between 300 fathoms and the surface were remarkably rich obtained It both in evident that in the regions is unknown depth during animals sink to an noted that these same animals surface hauls made cessful than those Among number and at night made the we examined the daytime rise to the surface is in the free expanse of ocean same It should also during the night, for our The relatively great In continents number of the the open sea, however, they in the Rhopolonema, Aglaura, and Liriope, There were, however, two young of between California and the Marquesas were wonder- Leptolina forms were captured near some coast or A suc- number Our hauls pelagic types while yEgina and Solinaris were met with occasionally : be locality during the day fully rich in such Trachylina forms as rule pelagic the quite striking, for these medusae are rare in waters coasts of constituted the greater archipelago specimens were almost without exception much more Trachylina and thirteen Leptolina forms adjacent to the Hydromedusas obtained by the " Albatross," seven are the twenty the Trachylina forms of variety Sarsia where the nearest land was obtained (the in among remarkable N Lat Almost 9° 45', all of the the islands of an exceptions to this W Long 137° 47', Marquesas) was more than 1000 miles away ; In general, how- and a Tiara was found 600 miles north of the Marquesas ever, the results support the conclusions of Maas, in the case of the Plankton Expedition, that Leptolina forms are creatures of the shallower waters near coasts, while the Trachjdina are animals of the open ocean Maas, O., 1893; Craspedoten Medusen der Plankton-Expedition Also Marine Animals, Natural Science, London, Vol II., p 02—99 Distribution of On some Problems of the ; MEDUSAE The following table will serve to 141 show the extent of our captures: Number of Species obtained Hydroinedusse Number new Siphonophorae 10 4 42 21 The following forms Atlantic by are represented of Species already known 11 Scyphomeduste Ctenopborae Number of Species to Science 20 — 21 both the Tropical Pacific and in identical or very closely allied species : Aglaura prismatica, Liriope hyalina, Nausithoe punctata var pacifica, Abyla quincunx, Necto- physa Wyvillei ? DESCRIPTION OF THE SPECIES HYDROMEDDS^l Sarsia A single specimen of a young sp damaged condition was Sarsia in a greatly found on the surface when the nearest land (the Marquesas Islands) was remarkable that over 1000 miles away It have been taken so out upon the open ocean S-'; « far Station 13 ; is September 5, 1899 ; N Lat 9° Tiara oceanica, Plate The bell is and there medium is size, acorn-shaped and Long 137° 47' 1, fig mm in height and sixteen short tentacles The walls are very thin, There are eight long, eight The long ones The medium ; f W are about as great tentacles are about one-third as — S) S d indicates a surface tow made in the daytime S" a surface tow made at niirht (150 f made with an open net dragged between 150 fathoms and the surface during the day S)" indicates the same made at night indicates a haul (150 57', form should sp nov a small, solid, apical projection in extent as the bell height this Leptolina — ; rf EXPEDITION OF THE "ALBATROSS," 142 and the small ones are mere rudiments long, The from the hell-margin 1899-1900 All of the tentacles arise and intermediate ones basal bulbs of the long are conical, and each one bears a single ocellus upon The velum base is by means aboral side near the There are four narrow radial tubes, well developed the mid-regions of which display jagged edges the radial canals its The proboscis is The proboscis is of four mesenteries bound to short and extends only about one-half of the distance from the inner apex to the The gonads occupy velum four radially The surfaces of which are complexly folded much The folded and the the four lips are large and are proboscis and tentacle bulbs are of a delicate purple-pink A dark red ocelli are situated linear swellings, was found about 600 miles single specimen north of the Marquesas (250 f — Station 1G; September S)''; 9, 1809; N Lat 2° Turris pelagica, Plate The bell is mm 16 wider at the middle than The projection bell walls are about thirty short tentacles, arise are no The velum ocelli flat any other is There end is very thin and quite being of the same size a small, solid, apical flexible There are These tentacles all There conical and quite broad, being narrower near the circular canal than Their outer edges are jagged, excepting in the narrow place part of the bell-cavity four mesenteries The It is developed, complexly crenulated light port-wine color, numerous lips The and the gonads and single specimen of this Station ; by means of from the inner apex of the surfaces of the gonads are papilla? lips There are four well and tentacle bulbs are of a radial canals are of a medusa was found August 26; N Lat 31° the greater radially situated double rows The outer transversely folded and give rise to fills to the four radial canals of the distance opening large and is The gonads occupy four bell-cavity to the velar S''; proboscis bound which extend about two-thirds A being There are four radial tubes well developed parts near the circular canal shade 22' sides are barrel-shaped, from the bell-margin, and their bases are large and which are at all Long 137° 1, fig either at W sp nov and the in height, 38', 10', W still lighter in a surface haul Long 125° MEDUSAE PSYTHIA, 143 gen nov Williadae with four simple unbranched radial canals In all known genera previously The general form, are branched of the family Williadae the radial canals color, budding of the present medusa, however, the Williadae may It atavistic sport medusa-buds before attaining its Plate its may flatter give rise much shrivelled b}' con- ascertained It radially situated tentacles, each of one-half as long as the bell-height composed of chordate cells, The entoderm of and a very fine throughout the length of each tentacle radial canals ; appeared, than a hemisphere, and nun in diameter The gelatinous substance was of uniform and only moderate stiff, to 1, fig exact shape could not be however, to be slightly There were four among sp nov In the single specimen obtained, the bell was so that it complete development Psythia prolifera, traction, to place from some of the more an immature individual which or Williadae, one incline all be a primitive, or ancestral, form in which the canals have remained simple, or possibly an complex shape of proboscis, and method of thickness which was about these tentacles axial canal appeared to There were four and a simple, slender, circular canal was extend straight, simple, The proboscis was cruciform in cross-section, and about three-quarters as long as the height of the bell-cavity The four lips were small and slightly recurved Four medusa-bearing stolons arose from the four radial corners of the stomach very near the points of entrance of the four radial canals stolons gave rise to from When opment tentacles and about two to to six radial canals, as in sprinkled over with nematocyst stolons is ochre-yellow, of these in various stages of devel- be set free the young medusa possesses four simple trace of the proliferating stolons is medusa-buds Each all the adult ; but The ex-umbrella cells its proboscis shows no of the The entoderm other parts being colorless young medusa of the proboscis A and single specimen EXPEDITION OF THE "ALBATROSS," 144 1899-1900 of this medusa was obtained, in an open net towed between 300 fathoms and the surface, i—S) J (300 off ; Marokau Island, Station 136; October 28, 1899; S Lat 18° 08', VV Long 141° 49' Lymnorea Plate The top as about The broad is it of the bell short fifty a The and the sides mm sp nov 9-12 2, figs about is flare outward in diameter, bell-walls are thin, and quite and in a bell-shaped is about as high flexible There are tentacles which are each about one-half the length of stiff entodermal cores are cells ocellata, These tentacles are usually carried curled upward, and the bell-height their flat is The animal manner Paumotus Group and composed of vacuolated chordate solid basal bulbs of the tentacles are large, and each one mass of red pigment In addition to this there is a prominent ectoder- mal ocellus upon the ventral (lower) side of each distance centrifugally from the basal are four straight, narrow radial peduncle of the proboscis is bulb contains tentacle The velum is at short a There small The canals and a slender circular tube wide and quadratic cross-section, in and its lower portion, near the gastric region, consists of highly vacuolated ento- dermal cells mouth is The gastric part of a simple round opening the proboscis The entire is pear-shaped, and the proboscis extends about one-half the distance from the inner apex of the bell-cavity to the level of the velar opening one of which is There are four well developed oral tentacles, each about half as long as the height of the proboscis Each oral tentacle branches dendritically four times, thus giving rise to sixteen distal knobs Each knob thickly covered with a bristling cluster of fusiform cells In addition to these there are several patches of nema- bristles upon the sides of the main trunk of each oral tentacle nematocyst tocystic is The gonads are developed of the proboscis in four radial The entoderm of the tentacle bulbs The ectodermal part of the proboscis number of these medusas were obtained Makemo Island, is regions within the gastric part brick-red and of the gastric ocelli are black A on the surface in the lagoon of Paumotus, on October 23, 1899 MEDUSAE 145 Bougainvillia fulva Agassiz and Mayer p 162, PI 2, Agassiz and Mater, 1899 fulva Bougainvillia Mus Comp Zool., Vol XXXII., Bull ; Fig Plate 2, fig individual of this species was found An immature by us among the Fiji Islands in 1898, and a mature specimen was obtained off Funafuti Atoll, Ellice Islands, on The cal bell is December about 22, 1899 mm in The gelatinous substance height and the sides are straight and vertiis There of uniform thickness everywhere are four bunches, each containing seven tentacles, which arise from the bases of the four radial canals chordate cells are A These tentacles are solid single dark-colored ocellus is and their entodermal upon the under situated The velum or centripetal side of each tentacle near the basal bulb There are four narrow The proboscis vessel is straight, narrow, radial canals quadratic, and its base is is and a slender circular wide It extends about one-third of the distance from the inner apex of the bell-cavity to the velar Four opening oral tentacles, each of which branches dichotomously four times, arise from the four radial corners of the proboscis near the mouth The mouth The entoderm of proboscis The A The gonads are a simple round opening is the proboscis and tentacle bulbs tentacles are of a translucent milky color, and the bell single fathoms specimen was obtained in is rosin-yellow transparent an open net towed from a depth f — S)''; Station 195; December 1899; S Lat 10° 22, Epenthesis rangiroae, Plate 1, The is of 150 to the surface (150 The situated in the bell bell-walls are thin and W Long 179° is 30' sp nov Jig 4- slightly flatter than a hemisphere, is 47', and mm in diameter There are sixteen well developed flexible tentacles with large conical basal bulbs Sixteen otocysts, each containing a single spherical otolith, alternate in position with the sixteen tentacles The velum is broad narrow circular vessel There are four The proboscis 10 straight, slender, radial canals, is very short and quadratic and a in cross- EXPEDITION OF THE "ALBATROSS," 146 and there are four slightly recurved section, 1899-1900 The four gonads are lips found upon the four radial canals very near to the circular single specimen obtained, each The medusa eggs gonad contained from six to eight prominent transparent with the exception of the proboscis gonads is and tentacle bulbs, which are translucent and milky in was found In the vessel This form color lagoon of Rangiroa Island, Paumotus, on September 23, in the 1899 (150 f— S) d ; Station 195; December 22, 1899 ; S Lat 10° 47', Phortis elliceana, Plate The much bell is flatter 2, figs is 5-7 the bases of the four radial canals mm about 16 is in There are about sharp-edged is Four of these are hollow tentacle bulbs 30' thick at the aboral pole, but becomes thinner towards the bell-margin, which fifty-six Long 179° sp nov than a hemisphere, and The gelatinous substance diameter W Twelve others are three of these are found in each quadrant and are situated at large, medium of size, and In addition to these there are about forty very small rudimentary tentacle bulbs upon the bell-margin There are no marginal lateral or which alternate in cirri There are about position with the tentacle bulbs two or three spherical The velum otoliths is fifty-six otocysts Each otocyst contains four simple, narrow, radial canals, and a slender circular vessel cle is There are well developed The pedun- about as long as the bell-diameter, and projects a considerable distance The beyond the bell-opening basal part of the peduncle has the shape of a four-sided truncated pyramid, while the distal portion gradually toward the gastric part of the proboscis extend down the angles of the The proboscis latter recurved, crenulated is proboscis is is The long, and tapers four radial canals peduncle to the gastric portion of the short and flaring, and there are four well developed, The gonads lips are linear, and are developed the sub-umbrella regions of the radial canals bulbs and gonads is The entoderm of the tentacle pink in color, while that of the gastric portion of the A rosin-yellow single specimen of this medusa was found an open net which was towed from a depth of 150 fathoms to the f — Sy ; Station 195 ; December 22, 1899; S Lat 10° 47', W Long 179° in surface, off Funafuti Atoll in the Ellice Islands (150 upon 30' Tropical Pacific Medusae Plate 32 33