-NOKTH AMERICAN EARLY TERTIARY BRYOZOA. 193 



FIG. 50. Genus Caberea Lamouroux, 181G. 



A-C. Caberea cllixi Flt-ming, 1S2S. A. Zoariuni, natural size. B, C. Anterior and po.stciuir 

 sides of a zoariuru, X 50. (A-C, After Robertson, 1007. 1 



//. av., frontal avicularium. r, serrated vibraculum. 



Sir, the groove. v. ch,, vibracula'r chamber visible from the front. 



lot. av., the minute lateral avicularia. v. oh., vibracular chambers extending obliquely 

 ', the rootlets arising from each vibracular across the back of each zooecium. 



chamber and proceeding downward through 



the middle of the branch. 



D-H. Caberea aanvini Busk, 18S4. D. Lateral surface, X 25. E. Anterior surface, X 50. 

 P. Operculum, X 85. G. Avicularian mandible, X 250. H. Ova, out of the ovicell, X 85. (D-H, 

 After Waters.) 



I-K. Caberea boryi Audouin, 1S26. I. Longitudinal section of an avicularium, greatly en- 

 larged. 



ce, external layer of the ciliated organ. md, mandible (=endocyst). 



ci, internal layer of the same organ. muab, abductor muscle of the mandible. 



ciinl. mandibular cavity. inuad, adductor or retractor muscle of the man- 



rct, ectocyst. dible. 



epa, avicularian epiderm. pa, aborted polypide=ciliated organ. 



c/i/, facial epiderm. 



J. Longitudinal section of a vibraculum, greatly enlarged. 



cmd, cavity of the vibraculum (=eudocyst). muad, adductor mandibular muscle. 



ect, ectocyst. pa, aborted polypide=ciliated organ =peculiar 



t'pv., vibracular epidermis. body with ci, its internal layer and ce, its ex- 



md, vibraculoid mandible. terual layer. 



muab, abductor mandibular muscle. 



K. Median sagittal section of an embryo at one of the last stages of its development. It 

 presents almost the exact structure of the larva. (I-K. After Calvet, 1900.) 

 c, mantle. fom, neuro muscular bundles. 



citl, calotte (terminal bud). one, central nervous organ. 



co, corona. pfse, subectoderm nerve plexus. 



'/. vaginal diaphragm. pplv, papilla of the vibratile plume. 



ccto, oral ectoderm. tyi, inferior glandular system. 



(/>(, mesodermic thickening. *'.7.s, superior glandular system. 



fr, ciliated cleft. si, internal sac. 



L. CaTierca ellisii Fleming, 1S28. (After Waters.) Vibracular chamber seen from the 

 inside, a. b. vibracular chamber; B. r, continuation of the groove beyond the chamber. 



5580919 Bull. 106 13 



