650 W. I. Robinson— Two New Fresh-water Gastropods. 



Found in the " Painted Desert beds " of northeastern 

 Arizona. The species is named after Professor Gregory, who 

 collected the specimens. 



Limnea hopii, sp. no v. (Fig. 1, a, b and c.) 



Shell small, with moderately high spire. Whorls three to 

 five, the last ventricose and having a height equal to that of 



the others combined. Aperture sub-oval, 

 not seen. Size and proportions variable. 



External surface 



Smallest specimen, height 5 mm , width, 3-5 mm 

 Medium " "9 " " 5-5 " 



Largest " " 12 " " 8-0 " 



These shells closely resemble L. ativuncula White,* but 

 differ from it in having fewer whorls and in being broader 

 proportionately. The spire of L. ativuncula is slightly more 

 attenuated than that of L. hopii. 



Found in the "Painted Desert beds" of northeastern 

 Arizona. Specific name after an Arizona tribe of Indians. 



Both Limnea and Valvata are represented by numerous spe- 

 cies from the late Mesozoic to Recent time. As no undoubted 



* White, C. A., op. cit., p. 20, pi. iv, figs. 10 and 11. 



