NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 



65 



the presence of an ovicell. The retractor muscles of the polypide are attached in 

 one of the zooecial angles. This results in a dissymmetry of the opesium and of 

 the o'pesiules as in Steganoporella, Onychocella, etc. 



Like Waters, 1899, we have thought that Membranipora savartii Audouin, 

 1826, belonged to this group of species. It is in fact also provided with spinous 

 processes and rather frequently with a proximal denticular plate. But this analogy 

 is not sufficient; for, first, the opesium is symmetrical; second, we do not know 

 whether there are opesiules in the chitinous cryptocyst; third, the operculum is 

 totally different; and, fourth, there are only 15 tentacles. 



The characteristics of this genus are much more visible on Memhranipora 

 occultata Waters, 1887, wherefore we believe it wise to add it as a second genotype. 



D.Euritina 



A.Aspidostonia 

 E.Odontionella 



I ■w./* 



F. Foraminella 



G . Rhagasostoma 



Fig. 8. — Genera of the family Aspidostomidae Canu, 1008. 



A. As-pidosloma, Hincks, 1881. A. gigantmm. Busk, 1884, X 25. Recent. 

 B Labiopora Levinsen, 1909. L. crenvlata Levinsen, 1909, X 23. Recent. 



C. Cro((Topora Levinsen, 1909. 0. /o?ca(a. Levinsen, 1909, X 23. Recent. (A-C after Levinsen, 



1909.) 



D. Euntina Canu, 1900. E. emila D'Orbigny, 1S52, X 20. Cretaceous. 



E Odori(ionc//a Canu and Bassler, 1917. 0. ofci(?(a(a Waters, 1887. (After Waters, 1887.1 



F. Foraminella Levinsen, 1909. F. lepida Hincks, 1881, X 25. Recent. (After Hincks, 1881.) 



G. Rhagasostoma Koschinsky, 1885. R. hexagonmn Koschinsky, 1885, X17. Eocene. (After 

 Koschinsky, 1885.) 



