PALEONTOLOGY. 99 



This carination is very obvious in a certain species first described 

 in the geological reports of New York under the name of Strom- 

 bodes helianthoides, which subsequently has been selected as the 

 type form of the genus Heliophyllum (Heliophyllum Hallii), whose 

 only distinguishing character from Cyathophyllum rests in the 

 carinated surface of its lamellae. If this distinction had been 

 carried out strictly, and had all the forms agreeing in structure 

 with Cyathophyllum, and at the same time having the surface of 

 the lamellae decorated by carinse, been placed under the genus 

 Heliophyllum, little objection could be urged against the arrange- 

 ment, but no attempt has been made to do so. Milne-Edwards, 

 the founder of the genus, while he describes one form as Helio- 

 phyllum Hallii, comes out with another equally characteristic Helio- 

 phyllum under the designation Zaphrentis cornicula, simply be- 

 cause that species has a somewhat large septal fovea, its only 

 structural similarity to Zaphrentis. Other forms with the Helio- 

 phyllum character well developed he continues to consider as Cya- 

 thophylla, as, for instance, Cyathophyllum helianthoides, Cyath 

 hexagonum, Cyath. rugosum, etc. 



Carinated lamellae are also regularly observed in the genera Diphy- 

 phyllum, Acervularia, Phillipsastraea, and in others. Another con- 

 sideration depreciating the value of the carinations of the lamellae 

 as a generic mark is their frequent total obsolescence in specimens 

 which by all other characters belong to a certain carinated species. 

 Having the alternative before me then, either to adopt Heliophyllum 

 and to substitute that name for a great man}'' others well established, 

 or to restore a few species now named so to their nearest relatives, 

 the Cyathophylla, many of which participate in the same character 

 of carination, I felt inclined to take the latter course as the simplest 

 and most satisfactory. 



CYATHOPHYLLUM HALLH, Milne-Edwards. 



Synon., HELIOPHYLLUM Hallii, Milne-Edwards. 



Simple turbinate polyp cells, attached by the small basal apex, and 

 frequently by additionaP root-like prolongations from a part of the 

 side-walls. The conical shape of the cells varies considerably in 



