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 Membranipora 
occultata Waters, 1887, wherefore we believe it wise to adcl it as a second genotype. 
E. Odontionella 
Fig. 8.— Genera of the family Aspidostomidae Canu, 1908. 
A. Aspidostoma, Hincke, 1881. A. giganteum Busk, 1884, X 25. Recent. 
B. Labiopora Levinsen, 1909. L. crenulata Levinsen, 1909, X 23. Recent. 
C. Crateropora Levinsen, 1909. C. falcata Levinsen, 1909, X 23. t Recent. (A-C after Levinsen, 
1909.) 
D. Euritina Canu, 1900. E. eurita D’Orbigny, 1852, X 20. Cretaceous. 
E. Odontionella Canu and Bassler, 1917. O. occultata Waters, 1887. (After Waters, 1887.) 
F. Foraminella Levinsen, 1909. F. lepida Ilincks, 1881, X 25. Recent. (After Hincks, 1881.) 
G. Rhagasostoma Koschinsky, 1885. R. hcxagonum Koschinsky, 1885, X17. Eocene. (After 
Koschinsky, 1885.) 
