50 mEW YOEK STATE MUSEUM 



lines are sometimes visible with favorable preservation. The cardinal 

 spines are two or three in number on each side of the beak and are 

 directed outward. 



On the brachial valve a fold to correspond to the obscure median 

 sinus of the pedicle-valve is not always to be seen. So far as ob- 

 served, the multiplication of the striae of this valve seems to be 

 wholly by bifurcation. With respect to their interior characters, both 

 valves present normal structure with a considerable development of the 

 median septum in the pedicle-valve. 



This species is quite common and is identical with or closely 

 allied to a shell known to occur in the New Scotland limestone of 

 the Helderbergian in Albany county. 



The comparison of these shells with specimens of Ch. melonica 

 from limestone no. 8 of the Gaspe series, at Grand Gr6^'e on the bay 

 of Gaspe, Quebec, shows that the latter is a larger shell with a charac- 

 teristic parabolic outline and a more profuse striation. 



Ch. hudsonica however occurs in the Gaspe sandstones associ- 

 ated with Spirifer gaspensis, Leptostrophia blainvillii 

 Billings, etc. 



Chonostrophia complanata Hall 

 (=Ch,onetes danosoni Billings, Oeol. sur. Canada; Paleozoic fossils, 2:18. 1874) 



Plate 7, flg. 1-13 



1859. Ghonetes oomplanatus Hall, Paleontology of New York. 3 : 418, 

 pi. 93, fig. 1, a-d 



1892. Chonostrophia sp. n. Clarke, op. cit. p. 413 



This shell seems never to attain the size of the normal Oriskany 

 form, but it has in general the same outline and seems to present no 

 stable features on which a distinction from this species can be based. 

 The striation of the surface is extremely fine and when well preserved 

 is distinctly fasciculate, particularly about the beaks. Usually however 

 this is more or less obscured over the body of the shell, the striae 

 •becoming subequal and often very faint. At times a still finer con- 

 centric striation is apparent. The reversed convexity is quite strongly 



