124< ON THE FOSSIL CORALS OF THE 



Genus Heliophtlltjm:. — (Hall.) 



Generic characters. — Corallum simple or aggregate ; radiating septa 

 well developed, obliquely striated on their sides by tbin elevated 

 ridges, wbicb extend from tbe outer wall in an upward curved course 

 towards tbe centre. These ridges are connected by numerous thin 

 laminae which divide the spaces between the septa into small sub-len- 

 ticular cells. The transverse diaphragms are thin, flexuous and con- 

 fined to the central portion of the coral. 



The only difference between this genus and CyatliopTiyllum is the 

 absence of the curved strise from the septa of the latter. 



Heliophtllitm Eeiense. — (Billings.) 



Yery large, elongate, turbinate, straight or curved ; length, from 

 two inches to more than one foot ; diameter, one inch and a half to 

 three inches and a half; radiating septa, about one hundred and fifty 

 in a specimen nine inches in circumference. The free edges of the 

 septa in the cup minutely denticulated with from five to seven short 

 spines in the length of one line ; the same number of arched strise on 

 the sides of the septa. 



None of the specimens that I have seen are perfect, and the ex- 

 ternal characters, such as the form of the surface, whether smooth or 

 annulated, have not therefore been ascertained. The cup appears to 

 be deep, and to have an obscure fossette on one side. A specimen 

 one inch and a half in diameter seems to be, without much doubt, 

 referable to this species, and as there are others three inches and a 

 half in thickness, the size mUfet be very variable. The small speci- 

 men has only seventy-four radiating septa, or about half the number 

 of the large individuals. 



The distinguishing character of the species is the closeness of the 

 arched striae on the sides of the septa, and the minute denticulation 

 on their free edges. 



Locality and formation. — Lot 19, con. 3, "Walpole ; and Kama's 

 farm. 



Heliophtlltjm Oatitgaense. — (Billings). 



Very large, elongate, turbinate, straight, or curved, sometimes in 

 more than one direction ; cup deep, with a smooth space in the bot- 

 tom, and a septal fossette on one side ; free edges of septa, with the 



