1915.] 



NATURAL SCIENCES OF PHILADELPHIA. 



405 



The top of the head is gray, integument elsewhere cream-tinted. 

 The median area of the sole is whitish, twice as wide as either side 

 area, the latter flesh-tinted. 



The genitalia (PI. XIII, figs. 2, 10). — Penis very small and slender, 

 having a very short, weak basal sheath of a few loose fibres. The 

 papilla is coarsely annulated, very slender and long. The penis- 

 retractor muscle is inserted on the epiphallus, which is extremely 

 slender, not so wide as the vas deferens, but enlarged a trifle where it 

 joins the latter. There is no flagellum. Female organs as usual. 



Jaw having four or five unequal ribs, sometimes rather weak 

 (PI. XIII, figs. 6, 6a). 



MiNffiAL 

 HILL 



OuTLlNC oe San X/wier Hill from west, Jo^oR£■ll/^ 



STATION IN CENTER. 



SoNOKLLA- 



San XAvieR Hill 



Fig. 



7. — Plan of the Mineral Hills, scale 2 inches to a mile, with sketch of the 

 type locality of Sonorella eremita. 



In the genitalia, as well as the shell, this species resembles S. 

 papagorum, but it differs by having a smaller penis and by the very 

 slender epiphallus, which is actually smaller than the vas deferens 

 in several specimens dissected. In S. tumamocensis the penis is 

 very much longer. The shell is smaller than S. popagorum, with 

 far more strongly developed apical scidpture than in any other species 

 of this cUstrict. It is also more solid, and, having an aspect of its 

 own, is not likely to be confused with any other Sonorella knoA\Ti 

 to us. 



The size is quite variable: 



