228 



THE HOLOTHURIOIDEA 



tube-feet and dorsal papillae present (exc. Capheira). Often auditory 

 vesicles on the radial nerves. Stone-canal single ; madreporite frequently 

 opening to tlie exterior. Respiratory trees absent (or rudimentary). 



Fio. III. 



1. Left side view of Deima i-alidum, Theel. (After Theel.) 



2. Ilyodaemon maculatus, Th. (After Theel.) 



3. (A) C-shaped spicule of Scotoitianes albida, Th. ; (B) wheel of Pannychia moscleyi, Th.; 

 (C) four-armed spicule of Elpidia rigida, Th. (After Theel.) 



4. Peniagone wyvillii, Th. (After Theel.) 



5. Psyehropotes longicanda, Th. (After Theel.) 



6. Ventral view of Elpidia glacialis, Th. (After Theel.) 



7 and 8. Side view and oral view of Pclagothuria natatrix, Ludw. (Modified from Ludwig.) 



9. Section through the madreporite and genital papilla of Ilyodaemon maculatus, Th. 

 (After Theel.) 



10. Portion of the intestine and rectal "cloaca," with its caecum, of Benthodytes 

 sanguinolenta, Th. (After Ludwig.) 



a, anus ; br, brim ; b.w, body-wall ; d, rectal " cloaca" ; coe, caecum ; d, disc ; d.a, dorsal 

 appendage ; g.d, genital duct ; g.h, genital aperture ; g.p, genital papilla ; i, intestine ; m, 

 mouth ; op, opening of pore canal ; p, tube-foot ; p.c, pore canal ; pp, papilla ; pr, anterior 

 process ; r, ray of the disc ; s, creeping sole ; s.c, stone canal ; t, tentacle. 



Calcareous ring of five or ten pieces. Spicules various, frequently in the 

 form of wheels and four-rayed spicules. SUB-FAMILY 1. PSYCHROPOTLXAE. 

 Body surrounded by a brim. Mouth quite ventral. Dorsal papillae 

 usually small. Tube-feet small, as a rule on the three ventral radii. 

 Calcareous ring incomplete, the interradial pieces being represented by 



