NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
403 
shelter from extraneous influences. The orifice of this chamber is irregular; it is 
not a peristomice, since it has no peristome. The tentacles must necessarily be 
long and flexible. 
The locella is the equivalent of the peristomie; it assumes the same functions 
with great economy of calcification. 
Fig. 118. — Anatomy of the Peristomellae Canu and Bassler, 1917. 
A-G. Peristomella coccinea Abildgaard, 1805. A. Free larva seen in profile, showing the 
slightly exposed disposition of the corona and the relatively small size of the terminal bud, 
X 75. B. Free larva, oral face, X 50. C. Free larva, aboral face, X 50. (A-G after Barrois, 
1877.) cal, calotte (terminal bud); CD, digestive cavity; ft, flagellum; mi, aboral mesoderm; 
ms, oral (labial) mesoderm; oc, oeuliform points; ph, pharynx; PI, vibratile plume; RV, border 
of the calotte. D. Zooecia, X 30. (After Hincks, 18S0. ) E. Operculum, X 85. (After 
Waters, 1878.) F. Mandible, X 85. (After Nordgaard, 1904.) G. Avicularian mandible, X 
23. (After Waters, 1885.) 
H. Peristomella prestans Hincks, 1882. View from the basal surface showing dietellae, X 
23. (After Levinsen, 1909.) 
I. Exochella longirostris Jullien, 1888. Polypide seen anteriorly, X 210 ; the avicularium 
has been drawn at its place ; its muscular fibers are erect. The feeble development of the 
stomach is to be noted. (After Jullien, 1S88.1 est, stomach; int, intestine (?) ; mav, elevator 
muscles of the avicularian mandible; mo, opercular muscles: rnr, large retractor muscles of 
the polypide ; oes, esophagus.; ph, pharynx. 
The principal genera of this group are : 
Bathosella Canu and Bassler, 1917. 
Romancheina Jullien, 1888. 
Peristomella Levinsen, 1902. 
