320 



THE ECHINOIDEA 



The Atelostomata include two main divisions, which develop along 

 somewhat parallel lines. 



FIG. XL. 

 Compound fascicle on part of test of Macropneustes. (After Agassiz.) 



SUB-ORDER 1. ASTERXATA. 



Atelostomata with the peristome central and never bilabiate ; the 

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

 similar. Floscelle generally present. No sternum. 



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

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

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



an 

 s.a. -' 



S.a. 



FIG. XLI. 



Diagram of a Spatangoid Ecliinoid, showing arrangement of the fascicles, i, internal fascicle ; 

 a, peripetalous fasciole ; 7, lateral fasciole ; m, marginal fasciole ; s.a, subanal fasciole ; a.n, anus. 



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

 Desmoulins. 



FAMILY 2. NOCLEOLITIDAE. Asternata with sub-petaloid ambulacra 

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

 thopygus, Cott. ; Botriopygvis, d'Orb. ; Caratomus, Ag. ; (?) Desorella, Cott. ; 

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

 Oligopodia, Dune. ; Oligopygus, Lor. ; Pygaulus, Ag. ; Trematopygus, d'Orb. 



