NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
193 
Fig. 50. — Genus Caberea Lamouroux, 1810. 
A-C. Caberea ellisi Fleming, 1828. A. Zoarium, natural size. B, C. Anterior and posterior 
sides of a zoarium, X 50. (A-C, After Robertson, 1907.) 
fr. av., frontal avieularium. v, serrated vibraculum. 
!/r, the groove. v. ch., vibracular chamber visible from the front. 
lat. av., the minute lateral avicularia. v. ch., vibracular chambers extending obliquely 
r, 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 darwini Busk, 1884. D. Lateral surface, X 25. E. Anterior surface, X 50. 
F. Operculum, X 85. G. Avicularian mandible, X 250. H. Ova, out of the ovicell, X S5. (D-H, 
After Waters.) 
I-K. Caberea boryi Audouin, 1826. I. Longitudinal section of an avieularium, greatly en- 
larged. 
ce, external layer of the ciliated organ. 
ci, internal layer of the same organ. 
and, mandibular cavity. 
ect, ectocyst. 
epa, avicularian epiderm. 
cpf, facial epiderm. 
J. Longitudinal section of a vibraculum, 
cmd, cavity of the vibraculum (=endocyst). 
ect, ectocyst. 
cpv, vibracular epidermis. 
md, vibraculoid mandible. 
muab, abductor mandibular muscle. 
to d, mandible (=endocyst). 
■muab, abductor muscle of the mandible. 
muad, adductor or retractor muscle of the man- 
dible. 
pa, aborted polypide=ciliated organ, 
greatly enlarged. 
muad, adductor mandibular muscle. 
pa, aborted polypide=ciliated organ=peculiar 
body with ci, its internal layer and ce, its ex- 
ternal layer. 
K. Median sagittal section of an embryo 
presents almost the exact structure of the larva. 
c, mantle. 
cal, calotte (terminal bud). 
co, corona. 
d. vaginal diaphragm. 
ccto, oral ectoderm. 
epm, mesodermic thickening. 
fe, ciliated cleft. 
L. Caberea 
inside, a, 
at one of the last stages of its development. It 
(I-K. After Calvet, 1900.) 
fom, neuro muscular bundles. 
one, central nervous organ. 
pfse, subectoderm nerve plexus. 
pplv, papilla of the vibratile plume. 
syi, inferior glandular system. 
isgs, superior glandular system. 
si, internal sac. 
Vibracular chamber seen from the 
ellisii Fleming, 1828. (After Waters.) 
b, vibracular chamber ; b, c, continuation of the groove beyond the chamber. 
55899 — 19 — Bull. 106 13 
