1910.] NATURAL SCIENCES OF PHILADELPHIA. 59 



Alt 12.8 12.2 12.2 12.7 12 11.8 11.5 mm. 



Diam 21 21 20.5 20 19.2 19 18.5 mm. 



Ten adults from the slopes around the head of the southeastern 

 branch of Buckeye Canyon, Station 4, vary from 18.7 to 22 mm. 

 diameter (No. 94,325). 



Thirteen adults were taken at Station 5, near the head of Happy 

 Camp Canyon, only one alive. 



Alt 13 13 12.6 12.3 12.3 11 11.7 mm. 



Diam 22.3 21 20.7 20 20.2 20 19 mm. 



Alt 11.7 11.8 12 11.2 11 10.5 mm. 



Diam 19.2 19.2 19 19.2 19 18 mm. 



At Nine-mile Water-hole we obtained a single living adult snail and 

 8 young (No. 99,324). These, with a specimen taken by Mr. Ferriss 

 in 1905, indicate a large race at this place, with a slightly larger umbili- 

 cus than the types, and more closely approaching lip-ends (pi. I 

 figs. 4, 5). The soft anatomy, sculpture and color are like typical S. 

 bicipitis. Whorls barely 5. Two adults measure: 



Alt 15 15 mm. 



Diam 26 25.5 " 



Aperture alt 13 13 



" diam 14 14.5 " 



The genitalia are figured pi. Ill, fig. 2. 



Nine-mile Water-hole is a shallow amphitheatre open eastward to 

 the mesa, its slopes covered with great weathered boulders of coarse- 

 grained light gray granite, among which ferns grow luxuriantly. 

 A tiny stream trickles among the rocks, collecting into a stagnant 

 pool at the base. A man can make his way in the interstices between 

 and under the rocks, in some places, but as very few of them are 

 movable, it is almost impossible to obtain the shells. 



Specimens were dissected from Stations 1, 3, 4, 5 and from Nine-mile 

 Water-hole. All have a distinct sheath at the base of the penis, 

 attached also to the epiphallus and partially enveloping the latter 

 throughout a part of its length. This sheath varies from about one- 

 third the length of the penis in the type lot, to about a half in that 

 from Nine-mile. The penis-papilla in transverse section (fig. 7, pp.) 

 shows a group of minute ducts, but there seems to be a single terminal 

 orifice. The vagina is longer in the types than in other lots ex- 

 amined. 



