1918.] NATURAL SCIENCES OF PHILADELPHIA. 313 



next whorl has hyphen-Uke tubercles parallel with the suture, not 

 closely placed; subsequent whorls have famt growth-lines only; 

 there is no trace of spiral striae. 



The whorls are rather strongly convex, at first slowly increasing, 

 the last very wide, rather deeply descending in front. The aperture 

 is strongly oblique, nearly circular, faintly washed with ochraceous 

 within. The peristome is sharp, very little expanded except at the 

 columellar insertion where it is broadly dilated; terminations con- 

 nected by a rather long, quite thin parietal callus. 



Alt. 8.5, diam. 16 mm.; umbihcus 2.8 mm.; 4| whorls. 



Fort Grant, at foot of the Graham Range, Graham Co., Arizona, 

 the type. No. 58,121 A. N. F^. P., collected by Dr. George H. Horn. 



By the sculpture of the embryonic shell, as well as the general 

 appearance, this snail resembles Micrarionta hutsoni Clapp, which 

 is smaller, more depressed, with a larger umbihcus. It is somewhat 

 intermediate in form, between hutsoni and indioensis. If it reallj^ 

 belongs to Micrarionta, and there is no mistake about the locality, 

 it is- widely separated from its congeners. 



The single specimen has been in the collection for many years. 

 It had been labelled H. strigosa Gld. 



Dr. Horn, the distinguished coleopterist, was stationed at Fort 

 Grant sometime after 1863. He collected a number of shells in 

 that vicinity, which were described by W. M. Gabb in the American 

 Journal of Conchology for October, 1866, pp. 330, 331, as follows: 



Helix hornii Gabb. [Thysanophora hornii]. 



H. strigosa Gld. "The largest specimen I have seen of the species" 

 [ — Sonorella sp. undet.]. 



H. minuscula [Zonitoides minuscula alachuana.']. 



Pupa (Modicella) arizonensis Gabb [ = Pupoides marginaia var.}. 



Pupa hordacea Gabb [Pupoides hordacea\. 



The locality is given as "Fort Grant, at the junction of the Arivapa 

 and San Pedro Rivers;" but that junction is really a long day's 

 travel — fully fifty miles — westward; yet it may have been the 

 nearest definite landmark to be found on maps of the time. 



The "//. strigosa" mentioned by Gabb is a Sonorella 25 mm. in 

 diameter, of the S. hachitana group. The upper part of the peri- 

 stome is broken away, and the shell is bleached ; we do not recognize 

 the species. 



Of the Zonitoides several live specimens are preserved. They 

 probably came from around a spring. All of the other shells men- 

 tioned are such as live among rocks in arid foothills. The speci- 



99 



