260 PALEONTOLOGY OF NEW YORK. 



the rows being nearly or quite in contant ; on some fronds they are disposed 



in regular, oblique transverse rows, at an angle of about forty-five degrees 



to the axis of the branch. Peristomes thin, equally elevated, with 



several minute, spinuliform projections from the inner surface of the cell 



walls. Non-celluliferous margin and interapertur.al space with numerous, 



fine interrupted striae, which very frequently have the appearance of elongate 



mesopores ; height slightly less than that of the mesopores, from fifteen to 



eighteen in the space of 1 mm. 



« * * * * * * ** 



Formation and locality. Hamilton group, Fall-brook, four miles from Canan- 

 daigua, Ontario county, N. Y. 



Stictopora recubans, n. sp. 



PLATK LXin, FIGS. 20, 21. 



ZoARiUM consisting of a flattened, dichotomously branched frond proceeding 

 from a spreading base attached to other bodies ; branches frequently curved, 

 about 3 mm. wide, with margins essentially parallel ; non-celluliferous mar- 

 ginal space flat, width a little more than .50 mm. ; transverse section lenticular, 

 at .50 mm. from the margin abruptly contracting and extremely thin, the 

 remaining portion convex, the greatest thickness .50 mm. ; bifurcations 

 comparatively frequent, on the specimens observed occurring at intervals of 6 

 mm. or less. Cells tubular, those at the middle of the branch recumbent for 

 one-half their length, then abruptly bending and opening directly outward ; 

 marginal cells recumbent for nearly their entire length. The central ranges 

 of cells are parallel with the longitudinal axis, becoming more oblique as 

 they recede, the marginal ones being at an angle of about forty-five degrees 

 to the axis. The intercellular tissue consists of irregularly disposed vesicles. 

 Cell apertures circular, frequently pustuliform, diameter about .12 mm., 

 regularly disposed in longitudinal, nearly parallel rows ; six or seven rows 

 on a brtanch, separated by about twice the diameter of an aperture ; the 

 marginal apertures are slightly larger than the others, and a portion of the 

 cell walls is often exposed for more than half of its entire length. Peri- 



