WORTH AMERICAN EARLY TERTIARY BRYOZOA. 
373 
Ou the morphology of the Cheilostomata, Quarterly Journal of Microscopical Science, vol. 
46, pi. 17. 
The classification has been the object of study of Waters in 1898, 1909, and 
1913. 
The operculum has a projection on each side for muscular attachment: it is 
generally thick. The aperture bears two lateral denticles or cardelles serving as 
a pivot for the operculum. The ovicell is always hvperstomial. 
A Hippoporina 
h. Hippozeug- 
osella 
B. Hippoponella 
C. Hippo- 
menella 
D. Hippo- 
diplosia 
F. Hippadenella 
G. Hippopordla 
Fig. 113. — Genera of the subfamily Hippoporae Canu and Bassler, 1917. 
A. Hippoporina porcellana Busk, 1860. Recent. 
B. Hippoponella hippopus Smitt, 2867. Recent. 
C. Hippomenella mucronelliformis Waters, 1898, X 25. Recent. 
D. Hippodiplosia pallasiana Moll, 1803, X 20. Recent. 
E. Hippozeugosella arcuata, new species, X 20. Lower Jacksonian, Jackson, Mississippi. 
F. Hippadenella margaritifera Quoy and Gaymard, 1833, X 55. Recent. 
G. Hippoporella perforata, new species, X 20, Vicksburgian of Alabama. 
The distal part of the aperture is the anter; the proximal part is the poster. 
The cardelles separate the porta from the vanna. The porta serves for the passage 
of the tentacles. The vanna opens the compensation sac. which becomes filled 
during the extrusion of the polypide. We may suppose that the larger the vanna 
is the larger the compensation sac must be, and that, consequently the polypide 
bears more tentacles and that they are larger. 
