82 Forty-fourth Report on the State Museum, 



distinct, but the manner of growth and general appearance of the 

 two species are very similar. The curved branches, broad non- 

 celluliferous marginal space, the oblique and recumbent marginal 

 cells, will distinguish it from any other species at present known 

 from the Lower and Upper Helderberg and Hamilton groups. 



Formation and locality. — Hamilton group, shores of Seneca lake, 

 Seneca county, N. Y. 



Stictopora subcarinata. 



Stictopora ? subcarinata, Hall. Trans. Albany Institute, vol. x, p. 191, 1881. 

 " (s. g.?) dichotoma,'H.a\\. By error. Keport of State Geologist for 



1883, p. 48, 1884. 

 Stictopora subcarinata, Hall. Palaeontology of New York, vol. vi, p. 261, 



pi. Ixiii, figs. 1-6, 1887. 



When the fronds are well preserved this species will be easily 

 distinguished from Acrogenia prolifera by the entirely different 

 mode of growth ; where only fragments occur it closely resembles 

 that species in some of its aspects, but it may be distinguished 

 by the wider non-celluliferous marginal space, the fewer ranges of 

 cell apertures and the absence of striated longitudinal ridges, the 

 greater variation in size between the marginal and central cell 

 apertures, and the obliquity of the marginal apertures to the axis 

 of the branch ; when the central ridge is very prominent, and the 

 others are obsolete, it has some resemblance to Tceniopora exigua, 

 but generally the difference between the two species is well 

 marked. 



Formation and localities. — Hamilton group, two and one-half 

 miles east of Alden Station, Erie county ; Bellona, Yates county, 

 and York, Livingston county, N. Y. 



Semiopora bistigmata. 



Semipora bistigmata, Hall. Trans. Albany Institute, vol. x, p. 193, 1881. 



Eeport of State Geologist for 1883, p. 51, 1884 

 " '* ** Palaeontology of New York, vol. vi, p, 262, 



pi. Ixii, figs. 27-29, 1887. 



* -x- * ^ ^ ' ^ -x- * * 



This species is found associated with Stictopora incrassata, and 



its manner of growth is very similar, but it is easily distinguished 



by its much more slender form, smaller cell apertures, and inter- 



