NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
275 
Family COSCINOPLEURIDAE Canu, 1913. 
1913. Coscinopleuridae Canu, Etudes morphologiques sur trois nouvelles families de Bryo- 
zoaires, Bulletin Societe Geologique de France, ser. 4, vol. 13, p. 145. 
The apertura is semilumar, marginated, anterior, never terminal. The ovieell 
is hyperstomial, embedded in the distal zooeeia, never closed by the operculum. 
The onycliocellaria are straight but typical. 
The known genera are: 
C oscinopleura Marsson, 1887. 
E ' scharipora D’Orbigny, 1851. 
Macropora MacGillvray, 1895. 
Genus COSCINOPLEURA Marsson, 1887. 
1887. Coscinopleura Marsson, Die Bryozoen der weissen Schreibkreide der Insel Rugen, 
Palaeontologische 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 ) de- 
ep am Hagenow, 1810. 
Range. — Cenomanian-Thanetian. 
This genus is quite remarkable; it realizes 
the type of special adaptation to the mobile sub- 
stratum. 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 
zooeeia. 
The vibracula are powerful and their cilium 
must be very long; these are the zooeeia wdiose 
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 zooeeia (fig. 12). 
The hydrostatic zooeeia 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 DIGITATA Morton, 1834. 
Plate 2, figs. 7-22. 
1834. Eschara digitata 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 zooeeia showing salient trans- 
verse pore opening of ovieell. (After 
Canu, 1911.) 
