American Paleozoic Bryozoa. 27e 
bo 
into clearly differentiated ‘* mature” and “immature” regions, such as 
I have shown to mark, without exception, all of the Monticuliporide, 
if, indeed, not all of the TRepostomatTa. In this respect, Jdiotrypa 
more nearly resembles the Celleporide, and its affinities with that family 
of the CuEILostomatTa, is strengthened by the apparently poriferous 
condition of its horizontal and vertical partitions. On the other hand, 
however, Jdiotrypa is fundamentally distinguished from Cumulipora, 
and other members of that family, in having, as is clearly proven by 
tangential sections, two distinct sets of cells. From all of the Monti- 
euliporide, in which two sets of cells are present, this genus is further 
distinguished (that is, if we regard the horizontal partitions dividing 
the zoarium of Jdiotrypa, as equivalent to the diaphragms of the 
majority of the TREPostomata), by the equal tabulation of the inter- 
stitial and true cells, the diaphragms in the interstitial tubes of all the 
dimorphic Monticuliporide known to me, being more numerous than 
they are in the proper zoccia. 
Taking these various and important differences into account, I come 
to the conclusion that Idtotrypa should not be placed into the family 
Monticuliporide, but not knowing where else it might be more properly 
placed, and being unwilling to found a new family for the reception of 
a single species, I am forced, provisionally, to refer the genus to that 
family. 
Formation and lucality : Niagara group. I obtained my specimens 
from the lower calcareous portion of the formation, at Osgood, Ind., 
where the species is associated with species of Holocystites, Caryo- 
crinus ornatus, Say, Saccocrinus speciosus, Hall, and Callopora elegan- 
tula, Hall. 
ANISOTRYPA, 1. gen. 
Judging from the only species known, the generic characters are as 
as follows : 
Zoaria ramose, branches hollow, consisting of one or more distinct 
thin layers of cells, the inner side of each being lined by a slightly 
wrinkled epithecal membrane. Zocecia tubular, short, arising rather 
abruptly from the basal membrane. Walls in the “immature” region 
excessively thin, but abruptly thickened as they bend outward, and 
proceed directly to the surface. At a point marking the termination 
of the thin portion of the cell-walls, a diaphragm crosses the tubes at 
aright angle. True zoecial apertures placed at the bottom of an ex- 
panded vestibule. Interstitial cells, and spiniform tubuli, wanting. 
