6S 



in the middle. — Desmarets and Le Sueur, Bull, des Sc. 1814, 

 p. 54, PI. ii. fig. 9. 

 On the large fossil oysters of Sceaux. 



II. Cellepora. — A sublapideous polypifer, internally 

 porous, expanded in a crust ; or raised in flat, stiff, lobated 

 or ramose, slightly convoluted fronds, bearing cells on their 

 outward surface. The cells rather membranous, urceolated, 

 ventricose, close, rather projecting, and confused ; the mouth 

 constricted. 



Desmarets and Le Sueur have, in the Bulletin des Sci- 

 ences, already referred to, ascertained the existence of two 

 fossil species. 



1. Cell, meg astoma. — Incrusting ; with very distinct ovate cells, ir- 



regularly heaped together ; the mouth large. — Bull, des Sc. 

 1814, Al. ii. fig. 5. 

 On chalk fossils. 



2. Cell, glohulosa. — Incrusting ; with distinct globulous cells, and a 



transverse mouth. 

 On chalk fossils. 



The fossil celleporce are distinguishable from the fossil 

 Jlustrce, by their cells being urceolated and irregularly placed, 

 and by the constricted appearance of the mouths. 



No species of tuhiilipora has been found fossil. They 

 might be distinguished by their cells being longish, tubular, 

 and not connected together by any lateral adherence ; and 

 by their mouths being round and regular. 



Neither has any species of the genus discopora been de- 

 scribed as seen in a fossil state : they might be distin- 

 guishable by their form, which is that of a discoidal undu- 

 lated plate, the upper surface covered with numerous small, 

 short cells, in quincunx order, the mouth not being con- 

 stricted. They differ from the tubulipores, in the cells 

 being more sunk and less free ; and from the cellepores in 

 having no lobated, convoluted, or ramose expansions. 



