AMERICAN JOURNAL 



DESCRIPTIONS OP THREE NEW SPECIES OF LAND 

 SHELLS PROM ARIZONA. 



BY W. M. GABB. 



Helix Hornii, Gabb. — Plate 21, fig. 5. 



Description. — Shell small, openly umbilicate, depressed; cov- 

 ered with an opaque brown epidermis, which, under the glass, 

 shows minute oblique striations, and a few small, scattered 

 hairs; whorls 4|, the first 3 J forming a very low, nearly flat 

 spire, the last descending much more rapidly ; suture strongly 

 marked, especially between the last and penultimate whorl ; 

 umbilicus occupying about a third of the inferior surface, in- 

 distinctly perspective ; aperture oblique, subcircular ; lip sim- 

 ple, inner margins approximating. 



Dimensions. — Height '09 in., greatest diam. -16 in., smallest 

 diam. *13 in. 



Locality. — Fort Grant, at the junction of the Arivapa and 

 San Pedro Kivers, Arizona. Collected by Dr. G. H. Horn. 



Observations. — This pretty little shell is of nearly the same 

 size as IT. Cronkhitei, Newc, but can be distinguished by the 

 opaque brown color, and, in very perfect specimens, by the 

 presence of minute hairs; the whorls are proportionately a 

 little more elevated; the mouth a little more nearly circular; 

 the apex is flattened, instead of being regularly conical ; the 

 last volution descends more rapidly than the others, instead of 

 having the same angle as the preceding ones, and, finally, it 

 wants entirely the strong, cross sculpture so characteristic of 

 Dr. Newcomb's species. 



Dr. Horn also found at the same locality a very fine speci- 

 men of H. strigosa, Gld., the largest specimen I have seen of 

 the species. 



Besides these were two or three specimens of R. minuscula. 



