NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
43 
Fig. 1. — General Anatomy of the CReilostomata. 
A. B. Structure of a corneous eheilostomatous bryozoan, Bugula turbinata Alden, from the 
Atlantic at Plymouth, England. 
A. A small copy or zoarium, natural size. 
B. Portion of a branch, X 50, showing the zooid or polypide in various positions in the 
zooecium. a, a', avicularia in different positions ; ap, aperture of the zooecium covered by a 
membrane ; b, polypide bud attached to bb, the brown body — the degenerated remains of an old 
polypide ; m, mouth surrounded by the circle of tentacles ; two individuals show the tentacles 
partly expanded ; o, ovicell ; s, marginal spines. In this figure the avicularia of some of the 
zooecia have been omitted. (A. B. After Harmer, 1S96. ) 
O. Two zooids of the common bryozoan called the “Bird’s Head Coralline” ( Bugula avicu- 
laria Linnaeus), highly magnified. (After Parker and Haswell, 1910, with corrections.) 
an, anus; avic, avicularia; ernb, embryo enclosed in the ovicell (ooecium) ; coec, coecum; 
funic, funiculus; int, intestine; mo, mouth; oes, esophagus; ooec, ooecium (ovicell); ov, 
ovary; pit, pharynx; ret, large retractor muscles of polypide; sp, spermatidia; tent, tentacles. 
The ganglion which is not indicated, lies just below the middle of the stroke from mo. 
