42 
CATALOGUE OF ECHINIDA. 
10. Meoma ; peripetalous fasciole distinct, subanal fasciole in- 
complete. 
11. Eaorina ; peripetalous fasciole distinct ; subanal or la- 
teral fasciole none. 
12. Desoria ; peripetalous and lateral posterior fasciole distinct ; 
ambulacra ; vertex anterior. 
13. Schizaster ; peripetalous and lateral posterior fasciole dis- 
tinct ; ambulacra ; vertex posterior. 
14. Tripylus ; peripetalous and posterior fasciole distinct ; 
vertex central. 
*** Ambulacra superficial. 
15. Agassizia ; peripetalous and lateral posterior fasciole very 
distinct. 
1. Ambulacral pores obliterated near the crown. — Spatangina. 
a. Ambulacra rather cruciform , flat ; series of pores elongated. 
1. Echinocardium. 
Shell cordiform, very thin ; lateral ambulacra very much 
arched ; pores few and distant ; anterior odd ambulacra in a 
more or less deep groove, with very small pores ; sides of the 
odd anterior ambulacral groove with rather larger spines and 
larger pierced tubercles ; mouth very excentric, anterior ; vent 
on the upper part of the hinder edge, supported by a heart- 
shaped very prominent shield ; an internal fasciole sur- 
rounds the anterior ambulacra, and is prolonged to the apex 
between the lateral posterior ambulacra, so as to interrupt 
their convergence ; a subanal fasciole surrounds the cordiform 
shield, sometimes furnished with two ascending branches to 
the vent ; peripetalous fasciole none ; ovarial pores four, very 
close ; ocellar holes very small, external to the ovarial ones ; 
lower surface with larger tubercles and larger bristles on 
perforated tubercles, with broad smooth bands, corresponding 
with the lateral ambulacra ; spines in front of plastron larger, 
dilated at the top ; lower ambulacral area very narrow. 
Amphidetus, Agassiz , Ann. Nat. Hist. i. 301, 1838 ; Agassiz & 
Desor , Ann. Sc. Nat. vii. 1847, 11. 
Amphidotus, Forbes , Brit. Starf. 190. 
Echinocardium, Van Phelsum ? ; Gray , Ann. Phil. x. 1825, 8. 
Spatangus a, Fleming , Brit. An. 480, 1829. 
Spatangus a, Blainv. Diet. Sc. Nat. lx. 185. 
