ART. 13 



BRYOZOAN FAUNA CANU AND BASSLER 



59 



fronds in the Diastopora form (double face), having the same char- 

 acter. This is the structure of a large number of Cretaceous fossils 

 classed by Gregory, 1899, in the Petaloporidae and Clausidae. The 

 old genus which corresponds most to our recent specimens is Gavaria 

 Hagenow, 1851, where we have also tubes with dorsal gemmation on 

 a basal lamella and separated by irregular mesopores. However, we 

 have cylindrical expansions and not hollow colonies with dia- 

 phragms. 



As the ovicell is unknown we have adopted the genus of the old 

 zoarial nomenclature to classify this species in order not to create a 

 new term which might have to be eliminated after the discovery of 

 the ovicell. 



On our recent specimens, as moreover on many of the fossils, may 

 be noted grouped on the same colony the forms Berenicea and Dlasto- 



FlGURE 13.— CaVARIA PRAESANS, NEW SPECIES. A, LONGITUDINAL SECTION 

 OF A CYLINDRICAL BRANCH, X 16, SHOWING THE TUBES ADJACENT TO THE 

 MEDIAN LAMELLA. B, TRANSVERSE SECTION, X 16, EXHIBITING THE CYLIN- 

 DRICAL TUBES AND THE MEDIAN LAMELLA. THE SMALL PORES ADJACENT TO 

 THE LAMELLAE ARE TUBES WHILE THE MINUTE DISSEMINATED PORES ARE 

 MESOPORES 



pora. The classification based on the zoarial form is perfectly useless, 

 as in the Cheilostomata. 



Afjlnities. — Exteriorily this species resembles Tretocycloeda pel- 

 liculata Waters, 1879, in the presence of closed mesopores between the 

 peristomes. They differ in their internal structure. In Waters's 

 species the gemmation is peripheral and the mesopores are subpa- 

 rietal, as shown in the sections of Waters, 1879, and Canu and Bass- 

 ler, 1920. JNIoreover, under the name of Heteropora pelliculata 

 several species have been confused. The exact determination of 

 species w^itli mesopores can not be made without sections. 



Biology. — Our specimens, having been separated from their sub- 

 stratum, prove that only they came from the depths indicated by 

 their surrounding. Moreover, they were dead. The zoarial surface 

 is wrinkled transversely. These wrinkles overlap on the closures of 



