THE NAUTILI'S. 99 



these riblets to collect. Only a good lens reveals this sculpture, and 

 in specimens which have been collected dead, or cleaned by ordinary 

 methods, it is usually lost. Still, a sufficiently patient examination 

 will eenerally show some trace of it somewhere on most specimens. 

 Thys. conspurcatella, of eastern Mexico, the type of the genus, has 

 similar cuticular riblets, hut they are more widely spaced and rather 

 more persistent. 



In young and half-grown shells, if perfectly preserved, the riblets 

 bear rather sparsely scattered and long hairs, very delicate and easily 

 rubbed off. I do not know that adults ever retain them ; though in 

 several [Mexican species such hairs occur on the full-grown shell, and 

 many West Indian species hear close bristles. 



The foregoing observations are based upon the entire -cries of 

 specimens in the collection of Mr. E. II. Ashmun, which he most 

 liberally sent me for examination, and those in the collection of the 

 Academy, including Gabb's types. 



The published figures and descriptions of this species have much 

 to be desired. Gabb gives quite a good description, though none of 

 his specimens show 4-| whorls, as he states. The dimensions, 

 " height .09, greatest diam. .16, smallest diam. .13 inch " = 24^, 4, 

 3^ mm., are in a rough way accurate. The figures are bad. 



Binney's figures (Man. Amer. L. Sh., p. Hi'.', fig. 1 •">'.!) are too 

 narrowly umbilicated, the spire is too conic, and the terminations of 

 the lip do not approach enough. Moreover, they do not indicate the 

 surface-sculpture. The whorls arc described as " scarcely convex " 

 whereas they are unusually so ; the ends of the peristome are said to 

 be "hardly approaching" while they actually converge so as to 

 nearly meet in adult shells. The dimensions, " greater diam. 4, les- 

 ser 3i, height 1 mm." are erroneous, the largest in Gabb's type lot 

 measuring 4 mm. in greatest. 3.5 in hast diameter, with a height of 

 2.6 mm. An adult specimen from Jerome, Arizona, collected by 

 Mr. Ashmun. measures ; diam. 3.5, alt. 2.3 mm. 



Gabb's types were from " Fort Grant, at the junction of the Ari- 

 vapa and San Pedro rivers," in Graham Co.. southeastern Arizona. 



Mr. Ashmun has collected specimens in the following localities: 

 Jerome, Patagonia Mts., Crittenden, Prescott and Nogales, Arizona, 

 and Cook's, New Mexico. The International Boundary Commis- 

 sion collected homii at the summit of Hachita Grande Mt., ( rranl Co., 

 N. M., and Dall mentions seeing the species from the drift of the 

 Yaqui River, Mexico. No other localities are known for the species. 



