1918.] NATURAL SCIENCES OF PHILADELPHIA. 313 
next whorl has hyphen-like tubercles parallel with the suture, not 
closely placed; subsequent whorls have faint growth-lines only; 
there is no trace of spiral strie. 
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.; umbilicus 2.8 mm.; 45 whorls. 
Fort Grant, at foot of the Graham Range, Graham Co., Arizona, 
the type, No. 58,121 A. N.S. 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 umbilicus. It is somewhat 
intermediate in form, between hutsoni and indioensis. If it really 
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 hornit]. 
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 marginata var.]. 
Pupa hordacea Gabb |Pupoides hordaceai. 
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 ‘‘H. 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- 
