NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
335 
Evidently the hydrostatic and reproductive functions are identical in each 
but they operate in a quite variable manner. These variations added to those of 
calcification, which is also an important function, permits the establishment of a 
large number of genera almost all rather natural however, which facilitate the 
study of this very important family. The anatomical structure is given in detail 
for each group. 
Group 1. SCHIZOPORELLAE Canu and Bassler, 1917. 
Bibliography ( Anatomical ). — 1877. Barkois, Recherches sur l’embryologie des Bryozoaires, 
pis. 7, 8, figs. 8, 10, 11, 21; pi. S, figs. 30, 33, 35. — 1888. Jullien. Mission scientifique du Cap 
Horn, p. 48. — 1892. Waters, Observations on the Gland-like Bodies in the Bryozoa, Linnean 
Society Journal, vol. 24, pi. 19, figs. 6-13. — 1900. Calvet, Contribution A l’Histoire naturelle 
des Bryozoaires ectoproc-tes marins, pi. 10, figs. 8, 9 ; pi. 11, figs. 16, 17. — 1900. Waters, Bryozoa 
from Franz Josef Land, Linnean Society Journal, vol. 28, pi. 9, fig. 11 ; pi. 12, fig. 5. — 1902. 
Harmer, On the morphology of the Oheilo stomata, Quarterly Journal of Microscopical Science, 
p. 301, figs. 48-52; p. 303, fig. 46. — 1909. Waters, Reports on the Marine Biology of the Sudanese 
Red Sea, The Bryozoa, Linnean Society Journal, vol. 31, pi. 12, fig. 11. 
The operculum is semilunar; the proximal border bears a slit or rimule which 
opens the compensatrix. The muscular attachments are two small, symmetrical 
tuberosities more or less removed from the border. When the proximal border 
of the aperture is linear it serves as a pivot for the operculum ; when it is arched 
and the rimule very large the pivot of the operculum is formed by two projecting 
interior condyles. 
The text figure gives a presentation of the anatomical structure of the species 
of this group. 
The classification was attempted successively in 1899, 1904, and 1913 by 
Waters in considering the muscular attachments of the operculum. In 1888 and 
1903 Jullien formed many genera based on the nature of the frontal or on zoarial 
peculiarities. We will continue the work of these authors by considering the 
relationship of the operculum to the ovicell (passage of the eggs and escape of 
the larvae) . 
After the elimination of the genera created by Jullien and Levinsen, approved 
besides by Waters, a large number of very different species are still placed in 
the large genus Schizoporella Hincks, 1880. 
The group of Schizoporella viridis forming a part of the genus Watersipora 
Neviani, 1895, is provided with an endozooecial ovicell, and belongs provisionally 
to the family Hippopodinidae. 
The Schizoporella sinuosa group, in which the operculum does not correspond 
to the apertura and which is provided with a rimule spiramen, belongs to our 
family Stomachetosellidae. 
The Schizoporella unicornis group is quite well characterized ; the orifice of 
the ovicell is closed by a special membrane. This is our genus Schizopodrella. 
Hincks did not designate a type for his genus Schizoporella; the first species 
described is Schizoporella unicornis Johnston, 1847. We could (but it is not 
obligatory) preserve the name of Schizoporella for this group, but it seems to 
