398 

 4. The Viviparous Synapta of the West Indies. 



Hubert Lyman Clark, Fellow of the Johns Hopkins University. 



eingeg. 18. Juli 1896. 



During the past few months, I have had the opportunity of stu- 

 dying the anatomy and development of a viviparous Synapta, found in 

 Kingston harbor, Jamaica, very probably the species which Oersted 

 described in 1S50, under the name of Syjiaptula vivipara. At the 

 present time Oersted's species is one of the Synaptidae about which 

 little or nothing is known; it isso considered by Th eel in his systematic 

 review of the Holothurioidea in the »Challenger Eeportcc (Vol. XIV, 

 Part XXXIX, page 32) . It is hoped that the following description 

 will serve to define the species and give it its proper place in the group. 



External Characters: Length from five to fifteen centimeters; 

 diameter from three to five millimeters. Tentacles twelve, rarely thir- 

 teen, long and slender; sometimes one or two are longer or shorter than 

 the others; digits from 25 to 37, the older the animal, the greater the 

 number. Surface of the body very rough owing to the anchors in the 

 skin. Color, reddish — or greenish — brown of various shades, usually 

 rather dark and often with numerous ^^;hite spots, due to aggregations 

 of miliary granules. Body semi-transparent, the longitudinal muscles 

 and the intestine showing plainly. 



Internal Anatomy: Alimentary canal long and slender, with 

 a single simple convolution and somewhat enlarged to form the cloaca. 

 Haemal system simple but well-developed. Calcareous ring narrow^, of 

 12 — 13 pieces, five of which are pierced for the nerves; each piece is 

 simple without posterior prolongations of any kind. Cartilaginous 

 ring present, directly beneath, and of the same Avidth as the calcareous 

 ring. Water-vascular ring a little below the cartilage, with from two to 

 seven polian vesicles of various sizes, the largest being about six mm long. 

 Madreporic canal single and small, lying close beside the dorsal mesen- 

 tery. Genital gland usually w'ith tree main branches, situated ante- 

 riorly and dorsally, beside the mesentery and opening just above the 

 mouth, well within the ring of tentacles. Otocysts ten, arranged in pairs 

 beside the nerves, as usual. Ciliated funnels, very numerous on the 

 mesentery, short and rather wide, apparently not on long pedicels, as 

 in S. digitata. AU specimens examined, collected from the end of 

 aprii until the middle of July, contained more or fewer young in va- 

 rious stages of development. Average number from fifty to seventy-five; 

 maximum 176. Nearly always the young were of two ages, several 

 days apart; very rarely three broods were found. 



Calcareous deposits: Miliary granules present in great quan- 

 tities, often crowded together to form spots in the skin visible to the 



