NATURAL SCIENCES OF PHILADELPHIA. 183 



of the Helicidse^ with which I am not familiarl}' acquaiiitecl. 

 Another reason for snspecting that this might be the case is, that 

 we have from the same formation, somewhat farther northward, 

 another simiLar but more depressed form {H.veterna^ M,), which 

 has the same kind of surface-markings, with a slightly but un- 

 mistakably reflexed outer lip; while this latter shell stands, as it 

 were, exactly intermediate in form between the still more de- 

 pressed H. Leidyi, H. & M., from the White River territory', 

 and that under consideration. That these latter two shells (//. 

 Leidyi and H. veterna) really belong to some section of the genus 

 Helix, there seems to be no reason to doubt. 



Although believing the form under consideration to be related 

 to the two species last above mentioned, its unusually elevated 

 spire left me in doubt respecting its affinities. Consequently I 

 sent the best specimen in the collection (which, however, is a cast 

 retaining none of the shell) to Mr. Tryon, of Philadelphia, who 

 has studied the existing land and fresh-water Gasteropoda with 

 much care, and requested him to give me the benefit of his opinion 

 in regard to its relations; and he writes that he doubts the pro- 

 priety of viewing it as a land shell, or at least that he thinks that 

 if it be, it cannot belong to an}- of the existing North American 

 groups. He rather inclines to think it a Viviparus allied to V. 

 Joponica^ a species now inhabiting the streams of Japan. It 

 certainly has much the form of that species, though more de- 

 pressed. 



Without being entirely sure that it belongs to that genus, I have 

 concluded to refer the species provisional!}^ to Viviparus. If a 

 land shell, it would seem to be related to some section of the 

 genus Gochlosfyla, though probably not even then belonging to 

 any of the recent groups ranged under the same. 



Locality and position. Henry's and Black's forks. Church 

 Buttes, &c., Wyoming; Middle Territory. 



ISOCARDIA? HODGEI, Meek. 



Shell cordate-subtrigonal, very gibbous; length and height 

 nearly equal ; ' beaks elevated, gibbous strongly involute, and 

 placed in advance of the middle ; posterior dorsal side of valves 

 convex; incurved and sloping rather abruptly backward from near 

 the umboues; anterior side very abruptly truncated by a broad, 

 well-defined, large concave, cordate lunule, extending with the 

 1871.] 



