HOLOTHURIOIDEA 



365 



The family contains a considerable number of genera, which 

 are placed in two subfamilies, Elpidiince and Peniagonince. 



Key to the subfamilies and genera of Elpidiidce represented 

 in the N.E. Atlantic. 

 1. Calcareous deposits mainly pointed rods or 3 -radiate bodies ; 

 no true cruciform bodies. Rectum with a caecum. Sub- 

 fam. Elpidiince ........ 2 



Calcareous deposits mainly cruciform bodies (Fig. 217, 1, 2, 7) ; 

 rectum without a caecum. Subfam. Peniagonince . . 6 



Fig. 217. — Spicules of Peniagone porcellus (1), Scotoanassa translucida (2), 

 Elpidia glacialis (3, 4), Kolga hyalina (5), Periamma rosea (6), and 

 Peniagone ferruginea (7). 1, x 100 ; 5, x 100 ; 6, x 133. No exact 

 statement of magnification with the originals of the rest of these figures. 

 (After Perrier, ''Talisman'" Holoth. (1 and 6) ; Herouard, ''Monaco'', 

 xxi. (2) ; Theel, Elpidia (3 and 4) ; Ekman, Syst. phylog. Stud. Elasip. 

 und Aspidoch. (5) ; Grieg, " Michael Sars " Ech. (7).) 



2. Calcareous deposits mainly or exclusively pointed rods . 3 

 Calcareous deposits 3-radiate and C-shaped bodies (Fig. 217, 6); 



dorsal papillae only at the anterior end of the body, may be 

 united by a web ...... Periamma Her. 



3. Calcareous rods usually with a pair of long processes in the middle 



(Fig. 217, 4) ; wheels (Fig. 217, 3) present in small numbers ; 



