NORTH AMERICAN EARLY TERTIARY BRYOZOA. 



275 



Family COSCINOPLEURIDAE Canu, 1913. 



1913. Coscinopleuridae CANU, Etudes morphologiques sur trois nouvelles families de Bryo- 

 zoaires, Bulletin Society Geologique de France, ser. 4, vol. 13, p. 145. 



The apertura is semilumar. marginatecl. anterior, never terminal. The ovicell 

 is hyperstomial, embedded in the distal zooecia, never closed by the operculum. 

 The onychocellaria are straight but typical. 

 The known genera are : 

 C ' oscinopleura Marsson, 1887. 

 Escharipora D'Orbigny, 1851. 

 Macropora MacGillvray, 1895. 



Genus COSCINOPLEURA Marsson, 1887. 



1887. Coscinopleura MARSSON, Die Bryozoeu der weissen Schreiblcrekle der Insel Riigeu, 

 Palaeoutologische Abhandlungen, vol. 4, p. 71. 



The margins of the zoarium are bordered by large vibracula. The frontal is 

 deprived of pores and avicularia. 



Genotype. Coscinopleura (Eschara) cle- 

 </nsi Hagenow. 1840. 



Range. Cenomanian-Thanetian. 



This genus is quite remarkable; it realizes 

 the type of special adaptation to the mobile sub- 

 Ptratum. Very certainly the zoaria were at- 

 tached to algae in agitated waters. The zoarial 

 equilibrium, constantly compromised, was as- 

 sured by the vibracula and the hydrostatic 

 zooecia. 



The vibracula are powerful and their cilium 

 must be very long; these are the zooecia whose 

 frontal is perforated by large scattered pores; 

 the upper lip of the apertura' is quite salient, 

 oblique, truncated, conical. They belong to 

 the type of vibracula of the family of the Lun- 

 ulariidae. They are placed laterally on the 

 zoarial margins (fig. 13) and at the bifurcations they are often accompanied by 

 hydrostatic zooecia (fig. 12). 



The hydrostatic zooecia in our opinion, contained the liquid destined for the 

 zoarial hydrostatic system; they are therefore intended to augment the exterior 

 volume when they empty, and consequently diminish the weight and assure the 

 capacity to float. They are placed laterally (fig. 12) or they are grouped in large 

 number (fig. 21). 



Canu, in 1913, cited the known fossil species of this genus. 



COSCINOPLEURA D1GITATA Morton, 1834. 



Plate 2. figs. 7-22. 



1834. Eschara digltata MORTON. Synopsis of the Organic Remains of the Cretaceous Group 

 of the United States, p. 79, pi. 13, fig. S. 



FIG. 77. Genus Cianotremella Canu, 



1911. 



Cianotremella gigantea Canu, 1911. 

 View of zooecia showing salient trans- 

 verse pore opening [of ovicell. (After 

 Canu, 1911.) 



