MESOZOIC FOSSILS. 629 



area, and give the punctate appearance that suggested the specific name, 

 though it can hardly be considered a specific character, since it is common 

 in this and related genera. 



The species is represented by three imperfect valves from the divide 

 between Fawn Creek and Gallatin Valley, south slope of ridge south of 

 Gray Mountain, and west side of Snake River north of Berry Creek. The 

 specimen figured, which is from the second locality mentioned, measures 

 39 mm. in length and 19 mm. in height. 



In the well-defined radiating lines of the posterior area this species 

 resembles the Upper Cretaceous forms to which Conrad gave the name 

 Anatimya. 



Anatina (Cercomya) sp. 



Another species of this genus is represented by a single specimen from 

 the east side of Fan Creek Pass, which is too imperfect for illustration and 

 full description. It is much larger than A. punctata, measuring 76 mm. in 

 length, and it differs from that species in the outline of the anterior end and 

 in the entire absence of radiating lines on the posterior area. 



GASTROPODA. 



Neritina wyomingensis n. sp. 

 PI. LXXV, figs. 4 and 5. 



Shell small, consisting of about two and a half or three rapidly 

 increasing volutions ; spire very low and inconspicuous ; last whorl slightly 

 shouldered and forming about nine-tenths of the visible bulk of the shell ; 

 surface smooth, with rather distinct lines of growth near the aperture, 

 which has the thin sharp outer lip and straight inner lip with broad flat- 

 tened columella characteristic of the genus. The inner lip is smooth, or 

 nearly so, but the specimens are not in condition to show whether it bears 

 minute denticulations. 



Height of the type, 6 mm.; greatest breadth, 6£ mm. 



This species has a superficial resemblance to Neritina f phaseolaris 

 White from the Jurassic of Utah, but, besides slight differences in form, the 

 columella in that species is not flattened and the inner lip is not straight, so 

 that it has been referred to Lyosoma. 



The only other described American Jurassic Neritina is N. nebrascensis 



