378 ECHINODERMS OF THE BRITISH ISLES 



are known from the British seas, but six more may likewise be 

 expected to be represented there, viz. Benthothuria R. Perrier, 

 with the species funebris Perr., found off the Moroccan coast, 

 782-1230 m. (" Talisman ") ; Gephyrothuria Koehler and Vaney 

 (Syn. Himasthlephora H. L. Clark), with the species G. europeensis 

 Herouard, from 43° 45' 30" N., 9° 41' W., 2320 m. (" Princesse 

 Alice " ; only one specimen known) ; Paroriza Herouard, with 

 two species (see below, p. 386) ; Pcelopatides Theel, with two 

 species (see below, p. 388) ; Pseudostichopus Theel, with seven 

 species (see below, p. 386) ; Synallactes Ludwig, with the species 

 S. crucifera Perrier, from 30° 3' N., 14° 2' W., 2212 m. 

 (" Talisman " ; only one specimen known). 



Key to the genera of Synallactidce known from or likely to be 

 represented in the British seas. 



1. Genital tubes in a single bundle to the left of the dorsal mesentery. 



Tube -feet covering nearly the whole body. Deposits 3- or 4- 



radiate tables . . . . .1. Mesothuria Ludw. 



Genital tubes in c double bundle, one to each side of dorsal 



mesentery ......... 2 



2. Ajial opening in a vertical furrow, or situated at the base of a 



caudal prolongation ^ . . . . . . .7 



Anal opening not in a furrow nor at the base of a caudal pro- 

 longation ......... 3 



3. A marginal fringe along sides of body, which is rather flattened, 



with a distinct ventral sole ...... 4 



No marginal fringe along sides of body, which is more or less 

 cylindrical, without distinct ventral sole ... 6 



4. Body very broad and flattened ; marginal fringe strongly developed 



Pcelopatides Theel 



Body not very broad and flattened ; marginal fringe not strongly 



developed . . . . . . . . . 5 



5. Deposits cruciform .... 2. Bathyplotes Ostergren 



,, absent (?)■- .... Benthothuria Ferr. 



6. Ventral tube -feet and dorsal papillce disposed regularly along 



the ambulacra. Deposits cruciform, with a simple spire 



(Fig. 224, 9) Synallactes Ludw. 



Tube -feet and papillae irregularly distributed ; no deposits 



Paroriza Her. 



7. Anal opening in a vertical furrow. Skin usually covered with foreign 



bodies ; tube -feet all rudimentary . Pseudostichopus Theel 



Anal opening at the base of a caudal prolongation. Skin not 



covered with foreign bodies. A series of large papillae along 



each dorsal ambulacrum Gephyrothuria Koehler and Vaney 



^ Also in Paroriza the anal opening maj'-, on contraction, lie in a more 

 or less distinct longitudinal furrow. 



- It may perhaps be questionable whether Benthothuria can really be 

 maintained as different from Bathyplotes. 



