NORTH AMERICAN LATER TERTFARY AXD QUATERNARY BRYOZOA. 



69 



«''■*., 



Fig. 11. — Genus Diplodidymia Reuss, 1869. 



Figs. A-H. Diplodidymia complicata Reuss, 1869. 



A. Sketch, X 50 showing small sacs hanging from the opercular region, and in each an ovum grows 

 (or). At y. there seems as yet no ovum in the small sac; m., the muscles of the opesium. B. Section 

 showing an o"vn.im in the small sac, X 750. C. Section, X "50, in which the ovum has segmented and a 

 blastula has formed. D. Colony from Chuaka, Africa, X 6. E. Lower part of colony, X 25. F. 

 Portion of zoarium, X 85, showing the structure of the zooeciaand avicularia. G. Operculum, X 250. 

 H. Mandible of the avicularium, X 250. (A-H, after Waters, 1913.) 



Genus HEMISEPTELLA Levinsen, 1909. 



1909. Hemisepiella Levinsen, Morphological and Systematic Studies on the Cheilostomatous 

 Br>'ozoa, p. 164. 



No ovicell. The distal extremity of the cryptocyst plunges into the zooecium. 

 The dissymmetric opesium bordered laterally and inferiorly by spines. The two 

 opesiules, distinct or not are limited sometimes by the cryptocyst, sometimes by 

 the spinous processes. The opercular valve is garnished superiorly by an opercular 

 arch strongly chitinized. Small avicularium. Twenty-six tentacles. 



Genotype. — Hemiseptella (Vincularia) labiata Busk. 188-1. Range: iliocene- 

 Recent. 



Structure. — We have chosen Vincularia labiata as the genotype because it pre- 

 sents two sorts of spinous processes, the larger of which can unite in order to form a 

 bridge intended to support tlie hinge of the opercular valve. But this bridge is only 

 a secondary character. The cryptocyst covers the spinous processes. Levinsen 

 attributed to this genus a certain number of species from the Cretaceous figured by 

 D'Orbigny. This is an error; these species belong to the genus Floridina, for their 

 ovicell is endozooecial and they bear onychocellaria. 



