36 
CATALOGUE OE ECHINIDA. 
Var. 1. Back not so high, regularly rounded ; vertex rather 
anterior ; ambulacra narrow. 
c, d , e. With spines. 
/. Without spines ; ambulacra rather wider. 
Var. 2. Back regular, rounded ; ambulacra rather broad. 
Seba, iii. t. 10, f. 23-24. 
“ Echinolampas orientalis, Gray” Blainv. D. S. N. lx. 190, 
1830 ; Agassiz & Desor , 1. c. 163. 
Hab. Red Sea. Mus. Paris. 
a. Without spines. 
2. Echinolampas Richardii. 
Violet ; shell large, ovoid ; ambulacra broad. 
Echinolampas Richardii, JDesmoul. Tab. Syn. 340 ; Agassiz & 
Desor , 1. c. 163. 
Hab. Senegal. Mus. Paris. 
a. Without spines, in spirits ; ambulacral lines purple. 
Senegal. Presented by M. Petit. 
** The anterior porous band of the anterior pair of ambulacra 
shortest; under side rounded , convex ; mouth oblong, trans- 
verse , large , marked with no tubercles , and only very rudi- 
mentary oral ambulacra. 
3. Echinolampas depressus. 
Ovate, depressed, subpentangular ; back regularly convex. 
Echinolampas depressus, Gray , Ann. & Mag. N.H. 1851. 
Hab. ? 
a. Without spines. 
3. Mortonia. 
Shell ovate, thin, rather produced in front, rounded behind, 
covered with small tubercles ; vertex central, convex ; inter- 
nal cavity quite simple ; ambulacra petaloid, narrow, open at 
the end ; bands rather diverging ; pores rather crowded, united 
by an oblong groove ; beneath concave, especially near the 
mouth and vent ; mouth rather large, roundish oblong, trans- 
verse, without any ambulacral star ; vent large, transverse, 
oblong, in the middle of the space between the mouth and 
hinder edge; ovarial pores four; madreporiform plate small, 
central. 
? Echinocyamus, sp., Agassiz & Desor, 140. 
Mortonia, Gray, Ann. Mag. N. H. 1851. 
This genus differs from Echinocyamus in the thinness of the 
