Upper Helderherg Group. 



167 



apertures circular, four and sometimes five in the space of a fene- 

 strule ; middle of branch carinated. 

 Locality — Cherry Valley, N. Y. 



Fenestella adnata, n. sp. 



Infundibuliform ; width of branches from .35 to .50 mm., on non- 

 celluliferous side, sharply rounded or subangular, sinuous finely cari- 

 nated ; dissepiments, equaling or wider than the branches ; branches 

 sometimes anastomosing; fenestrules on non-celluliferous side circu- 

 lar, on celluliferous side oval, length .00 mm.; cells in from two to 

 four ranges, apertures circular, twenty-five in the space of five mm., 

 margins very strong. The margins of adjacent apertures frequently 

 unite and are prolonged, forming a short spine. 



Locality — Falls of the Ohio river. 



Fenestella nexa, n. sp. 



Infundibuliform, width of branch from .50 to .75 mm.; on non- 

 celluliferous side the branches are, when perfect, augular; dissepi- 

 ments, on non-celluliferous side .50 mm. in width, on celluliferous 

 side contracting midway between the branches to .25 mm., depressed, 

 carinated; fenestrules, subquadrangular or broadly oval, length 1.25 

 mm., width .75 mm.; cells in from two to four ranges, apertures cir- 

 cular, 16 in the space of 5 mm., longitudinally arranged; ranges sep- 

 arated by a strong, continuous ridge. 



Locality — Canada West. 



Fenestella mutabilis, n. sp. 



Infundibuliform, broadly spreading ; width of branches, near base, 

 .33 to .65 mm., above, from .65 to 1 mm. ; on non-celluliferous side, 

 near base, a slight carina along the middle; at a greater distance 

 from the base there are three or four strong striations ; dissepiments, 

 from .33 to .50 mm. in width, on the upper portion of the frond some- 

 times one mm., angular and carinated, or gently rounded without 

 carination ; fenestrules on the non-cellnliferous side oval or oblong, 

 length from .65 to 1 mm., width, .50 mm., but somewhat varymg; 

 cells in two and three ranges, apertures small, circular, seventeen in 

 the space of five mm., arranged in distinct longitudinal lines ; mar- 

 gins thin, distinctly elevated. 



Locality — Canada West. 



Fenestella porosa, n. sp. 

 Infundibuliform, coyical ; branches straight, width from .50 to .90 

 mm.; in well-preserved specimens the branches are angular, carinated; 



