1910.] NATURAL SCIENCES OF PHILADELPHIA. 61 



■quent whorls are lightly marked with growth-lines only. The aperture 

 is very oblique, subcircular; peristome thin, a little expanded, narrowly 

 reflexed below, the columellar margin dilated. Alt. 15, diam. 24 mm. ; 

 alt. aperture 11.7, width 13 mm. 



Penis small, usually shorter than the vagina, and less than one-third 

 as long as the spermatheca and duct. Epiphallus short, the flagellum 

 apparently absent or reduced to a very minute adnate ccecum (pi. IV, 

 figs. 1, 2, 3, 4, 5, 7). Radula with 35, 1, 35 (summit of Cross J Mt.) 

 to 38, 1, 38 teeth, about 14 laterals, an ectocone appearing on the 

 11th to 13th. The entocone is bifid on the outer 15 to 18 marginals, 

 and the ectocone occasionally so on some teeth, though generally 

 simple. Six radulse from 5 stations examined. The jaw has 5 ribs in 

 two, 6 and 7 in two other examples. The crops and oesophagus as far 

 as the stomach are conspicuously sulcate or corrugated longitudinally. 

 Type locality, head of Big Emigrant Canyon at Station 1, on a steep 

 slope shaded by pinyons, under large stones (limestone). The species 

 occurs in numerous colonies throughout Big Emigrant Canyon, except 

 on slopes with southern exposure. See map on p. 121. 



This handsome species, like others of the hachitana group, is ill- 

 characterized as far as the shell is concerned, but the genitalia are 

 characteristic by the small penis and absence of a free flagellum. In 

 the Chiricahua Mountains it is related to S. bicipitis of the Dos Cabezas 

 range, but in that the penis is well developed and the flagellum, though 

 small, seems to be invariably present. In all of the numerous exam- 

 ples opened the crop and intestine to the stomach are deeply furrowed 

 longitudinally, a condition observed in no other Sonorella. To what 

 extent this corrugation may be due to the state of the specimens is 

 uncertain. It happened that by some unaccountable oversight all 

 of the Big Emigrant Sonorellas were cooked and pulled without 

 drowning, and then were preserved in alcohol too strong to give the 

 best results. 



All of the following colonies but one are on limestone. 

 Type locality, Station 1. Thirty adult specimens were taken, ten 

 of them alive. They measure as follows: 



Diam. in mm 26 25.3 25 25 25 25 24.8 24.8 



Alt. in mm 15.3 15 16.3 14.9 14.2 14.2 15 15 



Diam. in mm 24.3 24.3 24.3 24.2 24.2 24 24 



Alt. in mm 15 14.6 14.3 15 14 16 15.2 



Diam. in mm 24 (three) 24 24 24 (three) 23.3 23 



Alt. in mm 15 14.5 14.3 14 14 14 



