O'CONNELL, REVISION OF THE GENUS ZAPHRENTIS 189 



Simple, elongated corallum, surrounded completely by an epitheca ; deep 

 <?alyx; a single, well-developed fossula, marking the abortion of the cardinal 

 septum ; no columella ; numerous, well-developed, serrate septa with carinae in 

 typical species; tabulse imperfect or absent; the septa prolonged generally to 

 the center of the visceral chamber. 



The forms such as gigantea, prolifica, and many others which are com- 

 monly considered as Zaphrentis, actually do not come under that genus 

 at all and consequently other generic terms must be sought. About con- 

 temporaneously with Zaphrentis appeared Lesueur's Caryophyllia comic- 

 ula, characterized by its simple, horn-shaped form, deep calyx, serrate 

 septa, and surface striae. This is the form which Edwards and Haime 

 identified with Zaphrentis phrygia and made the type of that genus. 

 Later Hall placed cornicula under Heliophyllum, mainly on account of 

 its well-developed carinas. Since the carinae are such an important fea- 

 ture in the type species, they cannot be omitted from later generic de- 

 scriptions, though more primitive species may be without them. Many of 

 the figures of Edwards and Haime's species show the carinas clearly as in 

 their Plate VI, figs. 1, la, Ic, Id. 



- II. The next generic name appearing in the historical development is 

 €aninia Michelin. C. cornucopiw has been definitely figured and de- 

 scribed as the type. It includes those curved forms with deep normal 

 fossula, numerous septa and tabulae, external striae and no carinae, which 

 are at present included under Zaphrentis. 



^ III. In 1872 Billings restricted certain species of Zaphrentis to 

 Heterophrentis, with H. prolifica as the type and having at most a single 

 tabula at the base of the calyx, a marked fossula, frequently a columella 

 or a low rounded elevation; septa generally alternating in size, the 

 smaller ones becoming obsolete as they approach the center, the larger 

 ones becoming elevated, sharp-edged and sometimes twisted. This may 

 be extended so as to include species with few tabulae such as Zaphrentis 

 simplex Hall. 



^ IV. The name Siphonophyllia of Scouler is revived for forms like 

 Caninia gigantea Michelin ; i. e., Zaphrentis cylindrica of Edwards and 

 Haime, which have numerous tabulae, a siphonofossula and a well-marked 

 external vesicular zone. 



V. Simpson in 1900 proposed Hapsiphyllum for zaphrentoids, with a 

 horseshoe-shaped inner wall, making Zaphrentis calcareformis Hall the 

 genotype. 



VI. Simpson also proposed Triplophyllum for forms which, like Za- 

 phrentis terehrata Hall and others, retained the alar pseudo-fossula?. 



