NORTH AMERICAN EARLY TERTIARY BRYOZOA. 755 



FIG. 244. Family Tubnliporidae Johnston, is:;s. 



A-D. Tiiluliporn flnbcllaris Fabricins, 1780. A, B. Free larva and optical section. C, D. 

 Aspect of the embryo at the beginning of the narrowing, drawing the projection more and more 

 strongly from the mesodermie thickening and from the mantle, erf. Digestive cavity; cm, 

 triangular portion of the body cavity between the fatty mass and the pharynx and the stomach; 

 mt, mantle: mi, fatty mass; o, orifice of the gastrula: s, oral face or from the vestibule. (A-D 

 after Barrois, ISTT. I 



E-G. Tubiiliitora pliirtanijca Couch, 1844. E. Polypide detached from the cell. F. Aspect of 

 the x.oarium with its polypides evaluated. (E, F, after Milne-Edwards. 1S3S. I <;. I it-generation 

 of the fertile polypide (stage K), X IT. The tentacles have lost their distinct outlines, and 

 are obviously degenerating. 



H. Stage B of Tubulipora plumnsn Thompson. 1S47. the embryo consisting of two blastomeres. 

 The caecum of the fertile polypide (which has not yet degenerated) is seen; f. and the corre- 

 sponding structure to the left are probably the degenerating follicles of eggs which are not de- 

 veloping. (After Harmer, 1898.) 



I-K. TubuUpora serpens (Busk, Smitt, Hincks). I. Polypide detached from the cell. ,T. 

 Ciliated embryo. (After Smitt, 1865.) K. Formation of the secondary embryos, a, primary 

 and secondary embryos; c. wall of the stomach; p, pharynx; R, large retractor muscle of the 

 polypide ; r, anus ; t, tentacles ; r, stomach. 



L-O. TuliuUpora plumosa Thompson, 1847. L. Fertile lobe, with one ovicell and the begin- 

 ning of a second ovicell; from a bilobed colony (proximal ends of oldest zooecia at tin- bottom of 

 the figure, obscured by foreign substance. M. Ovarian egg, in follicle (stage A). N. Decalcified 

 preparation of an old ovicell (stage G) with nearly solid embryophore containing numerous sec- 

 ondary embryos. The axial lobo of the embryophore ends in the oeciostome at o, and gives off 

 another lobe to the right. The main lateral lobe of the right side is only obscurely bifurcated ; 

 that of its left side is divided into five lobes. Z, proximal part of the ovicell, corresponding with 

 a zooecium. Greatest length of solid part of embryophore to tip of most projecting lobe. 2.5 mm. 



O. Orifices (apertures) of living zooecia. The terminal membrane has been somewhat re- 

 tracted. (L-O after Harmer, 1898.) 



P-R. Mesonea radians Lamarck, 1810. P. An example, X 25, showing ovicells with oecio- 

 stome (oe). Q. Section from the anterior to the dorsal surface of the zoarium, X So. showing 

 the lobes of the ovicell and the oeciostome (or) as well as the polypides (;>). The structure of 

 the wall of the ovicell is seen at the left (st) with one or two rosette plates at the base of the 

 broad pore tube. There is an outer membrane (m). R. Longitudinal section of the ovicell, cut 

 parallel to the anterior and dorsal surfaces. (After Waters, 1914.) 



