NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
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Fig. 55. — Subfamily Onychocellidae Jullien, 1881. 
A. Onychocella luciae Jullien, 1881. Portion of zoarium, X 47. B. Onychocella marion J ul- 
iien, 1881. Zooecia and onycboeellaria, X 47. (A, B after Jullien.) 
C-G. Yelumella levinseni Canu and Bassler, 1917. C. Ovicelled zooecia, X 55. In the cover- 
ing membrane of the aperture is seen a simple chitinized operculum, and in each of the two 
sinuses of the aperture the end of a parietal muscle. D. Longitudinal section through the endo- 
zooecial ovicell. E, F. Avieularium and inaudible, X 40. G. A zooecial operculum, above which 
is an ooecial operculum. (C-G after Levinsen, 1909.) 
H, I. Rectonychocella solida Nordgaard, 1907. Symmetrical mandible on the avieularium, 
X 48. (After Nordgaard, 1907.) 
J. Opercular valve of Onychocella luciae Jullien, 1881, X 47. 
K. Onychocella angulosa Reuss, 1S47. Mandible, X S5. (After Waters, 1885.) 
L. Opercular valve of Rectonychocella solida Nordgaard. 1907. 
M. Microstructure of a zooecium of Diplopholeos lineatum, new species, X 100. 
N. Vacuolar microstructure of an old zooecium of Rectonychocella semiluna, new 
species, X 25. 
cp , polypidian convexity. 
cry, cryptocyst. 
ect, ectocyst. 
k, lunate chitinous mass. 
me, corneous membrane. 
mo, opercular muscles. 
mr, elevator muscles of the mandible. 
onto, passage of the occlusor muscles. 
omr, passage of the elevator muscles of 
mandible. 
op, opesium. 
op, opercular valve. 
op, opesiular indentations. 
ov, ovicell. 
opov, operculum of the ovicell. 
pd, pivot with denticles. 
r, rachis. 
scl, sclerite. 
the v, vestibulum. 
