82 



LAND AND FRESH-WATER SHELLS OF N. A. [PART J. 



144. 



Fort Grant, Arizona, at the junction of the Arivapa and San 

 Pedro Rivers. 



My description and figure are drawn from an authentic 

 specimen. 



Helix mazatlaiiica, Pfeiffer. — Shell umbilicated, depressed, 

 with crowded rib-like stria, horn-colored ; spire somewhat convex ; whirls 

 four, rather convex, perceptibly increasing, the last round, 

 scarcely descending before ; umbilicus scarcely equalling 

 one-third the shell's diameter; aperture remote from the 

 axis, oblique, roundly lunate ; peristome simple, straight, 

 its extremities converging, that of the columella some- 

 what expanding in its upper portion. Greater diam. 2.^, 

 lesser 2 ; height scarcely 1 mill. 



Helix mazatlanica, Pfeiffer, Mai. Blatt. 1856, 43 ; Mon. 

 Hel. Viv. IV, 89.— Bland, Ann. N. Y. Lye. VIII, 

 164, f. 9. 

 Pseudohjalina mazatlanica, Tryon, Am. Journ. Conch. 

 Heli.ma.atlanica, ", 266, pi. iv, f. 59 (1866). 



enlarged. 



Mazatlan. 

 Fig. 144 is drawn from a specimen furnished me by Dr. 



Pfeiffer. 



Fig. 145. 



Helix asterisciis, Mouse. — Shell widely umbilicated, orbicularly 

 depressed, light brown, decussated by delicate incremental and revolving 

 strife and with from twenty-five to thirty delicate, thin, 

 transparent, prominent ribs, with waving edges and 

 inclined backwards, more like the epidermis than the 

 texture of the shell ; whirls four, the upper ones 

 flattened, the last globose ; suture deeply impressed ; 

 aperture subcircular ; peristome simple, acute, its 

 columellar extremity subreflected. Greater diam. 1^, 

 height ^ mill. 



Helix asteriscus, Morse, Proc. Bost. Soc. VI, 128 

 (1857).— W. G. BiNNEY, Terr. Moll. IV, 103, pi. 

 Ixxvii, f. 9.— Bland, Ann. N. Y. Lye. VIII, 163, 

 f. 8.— Morse, Amer. Nat. I, 546, f. 43 (1867). 

 Planogi/ra asteriscus, Morse, Journ. Portl. Soc. I, 24, 

 f. 50-52, pL ii, f. 5 ; pi. viii, f. 53 (1864).— 

 Tkyon, Am. Journ. Conch. II, 263, pi. iv, f. 55 (1866). 



From Gaspe to the north of Lake Superior, and through New 

 England. 



Helix asteriscus, 

 enlarged. 



