NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
701 
Fig. 230. — Family Crisiiclae Johnston, 1847. 
A-G. Crisia eburnea Ellis, 1755. A. Larva seen in profile. B. Aboral pole of larva. C. Oral 
pole. (A-C after Barrois, 1877.) CD, digestive cavity; s, oral face or from the vestibule. D. E, 
F. Embryos (after Smitt, 1865). G. Ovicell showing internal sac containing the primary em- 
bryos (after Smitt, 1865). 
H-M. Crisia denticulata Milne-Edwards, 1838. H. Section of a primary embryo. Two of 
the lobes of this embryo are provided with a central cavity and the two cellular distinct layers. 
The constriction which must cause the separation of the rest of the embryos is rather marked. I, 
J, K, L. Meridian sections showing different stages in the development of the secondary embryo. M. 
Sagittal section of an ovicell inclosing two primary embryos and a rather large number of sec- 
ondary embryos, cal , calotte; cce , external cellular layer of the secondary embryos; cci, internal 
cellular layer of the secondary embryo : co, coronna ; eh, primary embryo ; eb<, secondary embryo ; 
ect' ect", the two cuticular leaves of the ectocyst; ect a, aboral ectocyst; ecto, oral ectocyst; ep, 
endocys; <jt, tentacular sheath ; one, central nervous organ of the embryo; o, orifice; p, pores; si, 
internal sac; tm, mesenchymatous tissue; va, valvule. 
N. Crisidia ( Crisia ) franciscana Robertson, 1910. Cross section of an ovicell in an older 
stage of growth showing a relatively large embryo ( emb .) and a septum (sep) whose growth is 
about completed. The chitinous tube (chi. t) growing down into the ooecial cone ( oe . c ) shows 
only at intervals in this section. 
O. A cross section of an ovicell containing a developing embryo on a young stage (emb) and 
showing, also, an early stage in the growth of the septum (sep). 
P. Crisia edwardsiana D’Orbigny, 1839. Diagrammatic representation of a cross-section of 
the ovicell showing the cellular septum (sep) with the chitinous tube (chi. t) and chitinous floor 
(chi, fl). (O, P. After Robertson, 1910.) 
Q-S. Crisia ramosa Hariner, 1891. Sketches showing development of ovicell. The ovicell 
has in each case been numbered 4 in order to admit of ready comparison between the three stages. 
T. Crisia eburnea Ellis, 1755. A young internode decalcified, with a developing ovicell. 
(Q-T after Harmer, 1893.) A. B. C. Summits of an imaginary triangle. 
