LOWER SILURIC SHALES OF THE MOHAWK VALLEY IO5 



an a priori inference that this small specimen is no longer refer- 

 able toS. pulchella. A comparison of the figures of the 

 Pulaski type (plate 82, figure 12a) and of the Waterford speci- 

 men (i2c) shows marked difference in the position of the umbo and 

 the general outline. The latter belongs apparently to one of the 

 small Ctenodontas described from the Snake Hill beds; at any rate 

 it is not identical with the L. schucherti here described. 



Solenomya ? insperata no\\ 

 PL 6, fig. 13, 14 



Description. Shell rather small, very elongate, narrowing ante- 

 riorly, its length three times its height, greatest height one-sixth 

 the length from the posterior margin; little convex; the greatest 

 thickness not quite one-fourth the height. Umbones little promi- 

 nent, situated very posteriorly, one-eighth the length of the shell 

 from the posterior extremity; beaks apparently small and projecting 

 slightly above the hinge. Cardinal and basal margins straight, con- 

 verging gradually anteriorly ; posterior margin slightly concave above 

 and nearly vertical in the lower half ; anterior margin evenly 

 rounded. Umbonal ridge distinct and sharp, the anterior slope 

 evenly rounded in the posterior part and becoming rather flat in 

 front; the posterior slope steeply oblique, concave above (apparently 

 with an elongate elliptic area) and flat below. Surface with irregu- 

 larly spaced concentric folds which are most prominent on the 

 anterior slope and the umbonal ridge and numerous fine concentric 

 raised lines between and upon the folds. 



The interior characters have not been seen, no casts of the interior 

 having been obtained. 



Position and locality. Rare (but four specimens collected) in the 

 sandy mud shale of the Snake Hill beds at Snake hill, Saratoga 

 county, N. Y. 



Remarks. Doctor Ulrich writes me regarding this remarkable 

 pelecypod that its relations seem to be with Solenomya or Cli- 

 nopistha — both Devonic and Carbonic genera — rather than with 

 any Ordovicic shells known to him, the short end seeming to be 

 the posterior, and he suggests that the species belongs to Solenomya 

 or a new genus. As far as the shale material permits of observation, 

 the beaks are inclined toward the longer end of the shell, corroborat- 

 ing Doctor Ulrich's inference. Since our material does not give 

 any clues to the interior characters and there arc no important feat- 



