154 POLYGYRA. 



young H. appresta (pi. 50, figs. 6, 7), being flatter above, acutely 

 carinated, and more broadly umbilicated. 



H. ROPERI Pilsbry. PL 50, figs. 19, 20. 



Shell broadly umbilicated, flattened, subdiscoidal. resembling 

 in general form (but not in texture or sculpture), H. hartordiuna 

 Cooper and H. polygyrella Binn. & Bid.; rather thin, opaque, luster- 

 less, reddish chestnut-colored; surface delicately obliquely striated 

 above, smoother beneath, all over beset with short, delicate hairs. 

 Spire scarcely perceptibly convex, flat ; sutures moderately im- 

 pressed ; apex light-colored ; whorls 5-1, convex, very slowly widen- 

 ing, the last wider, rounded on the periphery and below ; slightly, 

 rather abruptly deflexed at the aperture, constricted immediately 

 behind the peristome. Aperture oblique, lunate-trilobate; per- 

 istome well expanded, thickened within, brownish, outer margin 

 bearing a square tubercular tooth within, basal margin bearing a 

 small tubercle near its union with the outer margin; parietal wall 

 with a long slightly curved transverse lamella, its upper termination 

 opposite the superior lip-tooth. Umbilicus broad and deep. 



Alt. 3, diam. maj. 8, min. 7 mill. 



Redding, at the head of the Sacramento Valley, Shasta Co., Cali- 

 fornia. 



H. (Triodopsis) roperi PILS., Nautilus iii, p. 14, figs. Polygyra 

 roperi W. G. BINN., Third Suppl. Terr. Moll. V, p. 212. ( Woodcut.) 



Three specimens of this species were found in river drift by Mr. 

 E. W. ROPER of Revere, Mass. The shell seems to be intermediate 

 in contour between H. (Triodopsis) loricata Gld. and H. (Polygy- 

 rella) harfordiana J. G. Cooper. It differs from the former in being 

 flatter, much more broadly umbilicated, with different spire and no- 

 tably different surface sculpture ; from the latter it differs in the 

 totally different texture and hairy surface. 



H. EDENTATA Sampson. -PL 50, figs. 16, 17, 18. 



Shell imperforate, much depressed globose, light brownish -horn 

 colored, somewhat translucent, but having an opaque buff streak 

 behind the peristome. Surface but little shining, showing under a 

 lens numerous short, low, cuticular lamellse, elongated in the direc- 

 tion of growth-lines (fig 18a.). 



Spire low, convex ; suture moderately impressed. Whorls 5, the 

 apical whitish, the last whorl abruptly, shortly deflexed in front, 



