HOLOTHURIOIDEA 427 



L. Galliennii (Herapath), from the Atlantic coasts of France ; and 

 L. miiiuta (Becher), known only from Heligoland. All of them are 

 littoral forms, not known from depths beyond ca. 50-70 m. As 

 these species are probably all found in the British seas, but 

 have been overlooked or confused with L. inhcerens, it has been 

 thought preferable to give descriptions of them and not only give 

 their characters in the key. 



Key to the species of Leptosynapta known frojn or likely 

 to occur in the British seas. 



1. Tentacles 10 2 



usually 12 (10-13)1 . . ". . . .3 



2. Tentacles simple. Besides anchors and anchor plates (Fig. 262, 4), 



small plates with 4 holes are found. Viviparous 



L. minuta (Becher) 



Tentacles usually with 2-4 pairs of digits. No 4-holed plates in 



the body wall. (Anchors, Fig. 262, 3) . L. decaria (Ostergr.) 



3. Tentacles usually with 5-7 pairs of digits, increasing in length 



distalwards. Intestinal canal straight ; no muscular stomach 



1. L. inhcerens (O. F. Miill.) 



Tentacles usually with 8-9 pairs of digits, not increasing in length 



distalwards. The intestinal canal forms a loop ; a muscular 



stomach present ........ 4 



4. Anchor plates of anterior end of body with serrate edge (Fig. 263) 



L. Galliennii (Herap.) 



Anchor plates of anterior end of body in the main smooth 



(Fig. 262, 1) . . . . L. bergensis (Ostergr.) 



1. Leptosynapta inhcerens (0. Fr. Muller). (Fig. 261.) 



(Syn. Synapta inhcerens (0. Fr. Miill.) ; Synapta duverncea 

 Quatrefages.) 



Tentacles 12 (exceptionally 10, 11, or 13), with mostly 5-7 

 pairs of digits, increasing in length distally, the outermost ones 

 being distinctly longer than the middle ones ; the unpaired 

 terminal digit is the longest. Alimentary canal not forming a 

 loop ; no muscular stomach. Ciliated funnels in three longi- 

 tudinal row^s, in median and left dorsal interradius and in right 

 ventral interradius ; at least in the left dorsal interradius they 

 form a close series in the whole length of the body ; in younger 

 specimens they may be almost totally wanting in the mid-dorsal 

 interradius. Usually a single Polian vesicle. Calcareous ring 



1 The number of the tentacles of the Leptosynapta species is not quite 

 constant, so that it does not offer a wholly reUable specific character, and 

 the other cliaracters should always be verified in order to obtain a reliable 

 identification. 



