370 PROCEEDINGS OF THE ACADEMY OF [June, 



a little recurved below; the margins approaching, parietal callus 

 short, thin except in old shells. 



Alt. 11.25, diam. 19.5, alt. aperture 10.5, diam. 9.25 mm. 

 " 12 " 20.5, " " 11, " 9.25 " 



Back dusky, tentacles dark, sole pale yellowish, with faint longi- 

 tudinal lines, demarking the areas, near the tail. 



Genitalia (PI. XI, figs. 4, 4a, No. 103,093, from Station 29).— 

 The penis is large, cyHndric, encircled by a small muscular sheath 

 at the contracted base, its retractor muscle inserted upon the apex 

 of the penis and the base of the epiphallus. The walls of the penis 

 are thin. Papilla (fig. 4a) nearly as long as the penis, stout, cylin- 

 dric, having obliquely longitudinal corrugation near the end, the 

 apex being obtusely conic with terminal pore. The flagellum is 

 longer than usual. Epiphallus is about equal to the penis in length. 

 The vagina is decidedly shorter than the penis. The duct of the 

 spermatheca is very long. 



Length of organs in mm. : 



No. 103,093.- — Penis, 10; epiphallus, 10; flagellum, 1.3; papilla, 

 8; vagina, 6; spermatheca and duct, 39. 



No. 103,094. — Penis, 11; epiphallus, 9; flagellum, 1.3; papilla, 

 7,5; vagina, 7. 



The jaw is highly arched, with five broad, unequal ribs. 



Dragoon Mountains. Types from Station 28, Bear Canyon, No. 

 103,094, A. N. S. P., collected by Ferriss and Daniels, November, 1910. 

 Also at Station 29, south of the Huzzar Mine, in the same vicinity. 



This species is related to Dos Cabezas species by the position of 

 the insertion of the penis-retractor, the cylindric penis-papilla and 

 the short vagina. It differs from all of these in its very large and 

 differently sculptured penis-papilla, and the thin shell, with rounded 

 aperture and minute granulation and hairs on the neanic whorls, 

 and a different pattern on the embryonic whorls. It is not closely 

 related to any species of the ranges further west. 



Other specimens, topotypes, from Station 28 measure: 



Alt. 11, diam. 21 mm. 

 " 11.3, " 20.5 " 

 " 10.8, " 19 

 " 10.2, " 18.5 " 



Specimens from Station 29 measure: 



Alt. 10.9, diam. 20 mm. 

 " 10.3, " 18 

 " 10, " 20 

 " 9, " 17.3 " 



