178 PROCEEDINGS OF THE ACADEMY OF [March, 



List of Species. 



HELICID^]. 



'Sonorella coloradoensis (Stearns). PL XII, figs. 26-30. 



Helix (Arionta) coloradoensis Stearns, Proc. U. S. Nat. Mus., vol. XIII, 



p. 226, pi. 15, figs. 6, 8, 12, 1890. 

 Sonorella coloradoensis Stearns, Pilsbrv, Proc. Acad. Nat. Sci. Phila., 1900, 



p. 560. 1901. Bartsch, Smithsonian Misc. Coll., vol. XLVII, p. 189, pi. 



32, fig. 3 (shell of type), 1904. 



The type specimen of this species measures: alt. 10, diam. 16.4 mm., 

 umbilicus about 1.8 mm. The locality given by Stearns and repeated 

 by Bartsch, 4 Grand Canyon of the Colorado opposite the Kaibab 

 Plateau, alt. 3,500 feet, is somewhat indefinite, on account of the 

 considerable extent of the Kaibab Plateau. Dr. C. Hart Merriam, 

 to whom we applied for further details, writes: "I collected the type 

 of Helix coloradoensis Stearns in September, 1889, in the Grand Canyon 

 below the tank then known as Canyon Spring, not far from where 

 John Hance afterward built what is known as the Hance Trail. At 

 that time neither the Bright Angel nor Bass's Trail had been heard of." 



This locality is, properly speaking, opposite what is now known as 

 the Walhalla Plateau, not the Kaibab Plateau. 5 As the river flows, 

 it is about 13 miles east of the Bright Angel Trail, and 30 miles east 

 •of Bass's Trail. Owing to the sinuosity of the sides of the canyon, 

 the actual distance along any level above the liver gorge and below 

 the rim would be at least three or four times as great. 



The specimens from the Bright Angel and Bass's Trails and from 

 the north side differ from the type by having the umbilicus slightly 

 larger. 



The soft anatomy of the type was not described. One of us has 

 ■dissected specimens from both sides of the river at Bass's Trail. The 

 genitalia of a shell from " Spectacle Cove" (Station A) figured (fig. 

 3 A) show the species to be a true Sonorella, related about as nearly 

 to the forms found in the region immediately south of Tucson, as to 

 any southern species. The penis (p.) is swollen distally, narrow in its 

 basal half, where it is enveloped in a rather long muscular sheath. 

 It contains a tapering papilla (p.p.), not quite half as long as the penis. 

 The epiphallus (epi.) is about equal to the penis in length, slightly 

 larger than the vas deferens. There is no flagellum. The penis 



4 The localities for S. coloradoensis in Inyo and San Diego Counties, California, 

 which Dr. Bartsch credits to Pilsbry and Johnson, were taken by them from a 

 paper by Dr. Stearns, Nautilus, VIII, p. 29. This paper was not noticed by Dr. 

 Bartsch, who has shown that the shells in question are not S. coloradoensis. 



8 See U. S. Geol. Survey Topographic Map, Vishnu Quadrangle. 



