96 PALEONTOLOGY OF NEW YORK. 



boidal peristome. There are also frequent short, interrupted striations 

 between the cell apertures. 



The characteristics of this species are so well defined that it will be readily 

 distinguished from any other. 



Formation and locality. Upper Helderberg group, west of Le Roy, N. Y. 



Stictopora perarcta. 



plate xxix, figs. 37. s8. 



Sticttrpora perarcta. Hall. Trans. Albany Institute, vol. x, abstract, p. 15. 1881. 



ReiwrtofStateGeologist for 188.'),advance8heete. Expl.pl.29,figs.37,38. 1886. 



ZoARiuM consisting of a flattened, bifurcating stipe ; width of branches slightly 

 less than 1 mm., margins parallel; transverse section lenticular; greatest 

 thickness about .40 mm. Cell apertures oval, length .20 mm., width from 

 one-half to three-fourths the length ; disposed in longitudinal parallel rows, 

 which are separated by prominent ridges ; five ranges on each face of the 

 branch. Peristomes thin, very slightly elevated. 



This species may be distinguished from S. linearis by its larger, oval cell 



apertures. 



Formation and locality. Upper Helderberg group, Onondaga valley, Onondaga 



county, N. Y. 



Stictopora linearis. 



PLATE XXVra, FIGS. 4, 5; ANU PLATE XXVU, FIG. 1. 



Stictopora liiiearis. Hall. Trans. Albany Institute, vol. x, abstract, p. 15. 1881. 



Report of State Geologist for 1882. Expl. pi. 2.5, figs. 4. 5. 1883. 

 " rectUatera (in error). Report of State Geologist for 1885, advance sheets. Expl. pi. 27, fig. 1. 



1886. 



ZoARiUM consisting of a flattened, dichotomously branching stipe ; transverse 

 section lenticular ; width of branches 1.50 mm., margins parallel; greatest 

 thickness .50 mm. Cell apertures circular, diameter .20 mm.; disposed in 

 longitudinal parallel rows, five or six rows on each face of a branch. Peris- 

 tomes thin, slightly and equally elevated. Rows separated by a narrow ridge. 



This species may be distinguished by its narrow branches, with infrequent 

 bifurcations and circular cell apertures. 



Formation and locality. Upper Helderberg group, N. Y. 



