320 



THE ECHINOIDEA 



The Atelostomata include two main divisions, which develop along 

 somewhat parallel lines. 



Fin. XL. 

 Compound fasciole on part of test of MftcroptUKtte*. (After A^assiz.) 



SUB-ORDER 1. ASTEHXATA. 



Atelostomata with the peristorne central and never bilabiate ; the 

 ambulacra simple, sub-petaloid, or petaloid, and generally all five are 

 similar. Floscelle generally present. No sternum. 



FAMILY 1. ECHINONBIDAE. Asternata with narrow, apetaloid, similar 

 ambulacra, and without floscelle. Genera Echinoneus, Van Phelsum ; 

 Galeroclypeus, Cott. ; Galeropygus, Cott. ; Hyboclypeus, Ag. ; Infraclypeus, 



an 



s.a. 



Fio. XLI. 



o, pen 



Diagram of a Spatangoid Kchinoid, showing arrangement of the fascioles. i, internal fas 

 )eripetalous fasciole ; l t lateral fasciole ; w, marginal fasciole ; s.a, subanal fasciole ; a.n, 



internal fasciole ; 

 anua. 



Qauth. ; Nucleopygus, Ag. ; Pileus, Desor ; Pachyclypeus, Desor ; Pyrina, 

 Desmoulins. 



FAMILY 2. NUCLEOLITIDAE. Asternata with sub-petaloid ambulacra 

 and no floscelle. Genera Amblypygus, Ag. ; Anochanus, Grube ; Anor- 

 thopygus, Cott. ; Botriopygus, d'Orb. ; Caratomus, Ag. ; (1) Desordla, Cott. ; 

 Haimea, Michelin ; Ilariona, Dames ; Nucleolites, Lam. (syn. EchinobrUsiui) ; 

 Oligopodia, Dune. ; Oligopygw, Lor. ; Pygaulus, Ag. ; Trematopygua y d'Orb. 



