596 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



Terminology. The zooecia parallel to each other are called oriented. They 

 are generally axial or marginal. 



The nonparallel zooecia, erect in every meaning of the word, are the cumulate 

 zooecia. Sections through such zoaria are very complicated and very difficult to 

 comprehend. 



The complete zooecia, the more exterior ones, are the superficial zooecia; they 

 give the better characters for classification, but they are often broken on the 

 fossils. 



The deep zooecia separate the superficial zooecia, but at a lower level; their 

 frontal is buried; their apertura and their avicularia are alone visible. Often 

 their avicularia are more salient than those of the superficial zooecia because they 

 endeavor to reach the level of the latter. 



The zoarial surface is in perpetual growth; the formation of the zooecia is 

 not simultaneous; there are therefore some incomplete zooecia. These are cavities 

 of greater or less size, which must not be confused with the avicularia. 



The interzooecial avicularia are very large. Their mandible is symmetrical 

 and articulates on a pivot or on two lateral denticles. These avicularia bear some 

 powerful muscles and they are adjacent to the superficial zooecia. 



The frontal avicularia of the deep zooecia appear interzooecial when they are 

 very salient; but they remain always attached to the deep zooecia, and they are 

 completely isolated from the superficial zooecia. 



Waters has best studied the classification of the Cellepores. In 1913 he gave 

 a first grouping, which certainly will be perfected in the future. The table below 

 sums up his opinion. 



Schizostomatous division (=Schismopora MacGillivray, 1888) : 



C. coronopiis-piimicosa group (Cellcpora Waters, 1915; CeUcpora Levinsen, 1909; Osthimosia 



Waters, 1913). 



C. eatoncnsis group (Osthimosia Jullien, 1SSS; Waters, 1904, not 1913). 

 C. costazzii group (Costazzia Neviani, 1S95; Lagcnipora Waters, 1S99; Siiiiopcita Leviusen, 



1909). 



Holostornatous division (=Holostoma, MacGillivray, 1S8S) : 

 C. descostilsii group (HoloporcUa Waters, 190.")). 

 C. sardonica group. 

 C. ramiilosa group. 



To this we add a third division : 



Clithridiate division : 



Acanthionella Canu and Bassler, 1917. 

 Kleidionella Canu and Bassler, 1917. 



We will adopt provisionally this classification and will discuss the names 

 adopted for each genus. But the natural classification may only be made by the 

 application of our system of physiological functions and in considering before all 

 the connection of the operculum with the ovicell. It will be necessary to commence 

 this work on the recent species. 



