Upper Helderherg Group. 



177 



carinated, prominently nodose, sometimes striated ; the branches fre- 

 quently appear as slight elevations across the dissepiments which are 

 apparently united; dissepments greatly expanded at the branches, 

 carinated, nodose. Fenestrules oval, length .90 mm., width .60 mm. 

 Cell-apertures in two ranges, with an additional aperture just below 

 the bifurcations, circular, sixteen in the space of 5 mm.^ carina thin, 

 height .50 mm., connected by lateral plates extending to the sum- 

 mit of branches, oblique. 



Locality — Canada West. 



Fexestella (IIemitrypa) substriata, n. sp. 

 Width of branches from .25 to. 50 mm., angular or subangular ; dis- 

 sepiments one-half to two-thirds the width of the branches. Fen- 

 estrules subqUadrangular, length .75 mm., width .35 mm. Cell aper- 

 tures in two ranges, circular, twenty in sjoace of .5 mm. Carina at 

 first thin, rapidly expanding to .35 mm., height Ad mm., connected 

 by lateral bars, fourteen in 5 mm. 



Locality — Falkirk, X. Y. 



Fexestella (Hemitrypa) elegaxtissima, n. sp. 

 Widtii of branches from .33 to .65 mm., rounded to angular, line- 

 arly nodose; dissepiments, width one mm., much expanded at junc- 

 tion with the branches. Fenestrules elongate-oval, length 1.50 mm., 

 width, 95 mm.; celluliferous side not observed. 



Locality — Canada West. 



Fenestella (Hemitrypa) favosa, 71. sp. 

 Width of branches from .20 to .35 mm., subangular, slightly cari- 

 nated. Fenestrules elongate-oval to subquadrangular, length to .45 

 mm., width .25 mm. Cell-apertures in two ranges, circular, twenty 

 in the space of five mm. Carina having processes from each side, 

 those of adjacent carinae connecting midway between the carinae form- 

 ing a ridge, interstices generally hexagonal. 



Locality — Canada West. 



Fenestella (Hemitrypa) cribrosa, ih sp 

 Width of branches from .25 to 50 mm., rounded, width of dissepi- 

 ments .18 mm. Cell-apertures in two ranges, circular, sixteen in the 

 space 01 five mm^ ; carina having lateral processes meeting midway 

 between carinas and uniting form a longitudinal ridge* interstices cir 

 cular enclosed by a narrow elevation 

 Locality — Falls of the Ohio river 

 23 



