CORALS AND BRYOZOA. 143 



g. Forms having the lateral processes or scald distant, and the dissepiments of the non- 

 celluliferous face with circular apertures. 



ISOTRYPA, Hall. 1885. 

 Fenestella (Isotrypa) conjunctiva. 



PLATE LIV, FIGS 10-21. 



Fenestdla (Hemiti-ypa) conjunctiva. Hall. Trans. Albany Institute, vol. x, abstract, p. 36. 1881. 

 Isotrypa bifaria. Hall, in error. Report of State Geologist for 1884, extract. Expl. pi. 2, figs. 13, 16. 



1885. 



Bryozoum infundibuliform, fronds large. Branches moderately slender, width 

 above a bifurcation .38 mm., increasing to .60 or .70 mm., straight, rounded 

 or angular, slightly carinated, sometimes small, at other times nodose ; on the 

 narrower parts of the branch the nodes are usually disposed in a row along 

 the middle of the branch ; on the wider portions in two or three rows, some- 

 times irregularly disposed, and at other times the branches, especially the 

 wider portions, are striated. Interstices slightly wider than the branches. 

 Dissepiments comparatively strong, width .40 mm., rounded, carinated, a 

 little depre.ssed, four in the space of 5 mm.; very frequently there is a com- 

 paratively large circular opening in the upper portion of the dissepiment, 

 having a diameter about .25 mm., the margins slightly elevated. This 

 aperture very rarely occurs in any other position. Fenestrules oval, length 

 .85 mm., width .40 mm. 



On the celluliferous face the branches are often slightly sinuous. Dissepi- 

 ments rounded, very much depressed. Fenestrules of about the same appear- 

 ance as on the opposite face. Cell apertures in two ranges, opening at an 

 angle of forty-five degrees, sixteen in the space of 5 mm., separated by less 

 than the diameter of an aperture : margins elevated, thin, slightly indenting 

 the borders of the fenestrules. Carina at first thin, expanding and having a 

 width of .33 mm. at the summit, which is angular and slightly carinated ; 

 carinas connected by scalae or pseudo-dissepiments of the same width as the 

 summit of the carina, angular, slightly carinated ; five in the space of 5 mm. 

 Interstices broadly oval or sub-quadrangular, length .67 mm., width .50 mm. 



