5S PROCEEDINGS OF THE ACADEMY OF [Feb., 



Nine-mile Water-hole, living deep under stones and rocks. Buckeye 

 Canyon is the first from the northern end of the range. Its upper 

 branches drain the eastern flanks of Dos Cabezas Peak. At the time 

 of our visit in November there was water at intervals in the stony 

 bed of the canyon as far down as our camp, near the reduction plant 

 of the Buckeye gold mine. Tarbox and Happy Camp Canyons unite 

 into a wide valley about a mile from the mesa. The mouth of this 

 valley is half closed by a great reef of light gray granite rocks which 

 forms a conspicuous landmark from the mesa. The country rock of 

 these canyons is mainly metamorphic, but in part granitic. 



This species has the same apical sculpture as S. bowiensis and 

 S. optima. It differs from optima in the shape of the penis-papilla, 

 the presence of a flagellum, the shorter inner cusp of the marginal 

 teeth, the larger aperture and narrower umbilicus. S. hachitana 

 from the Big Hachet Mountains has a decidedly smaller aperture. 

 In shell characters S. bicipitis stands nearest S. huachucana, but the 

 apical sculpture of the latter is much less distinct, without the oblique 

 threads on the last embryonic whorl which are characteristic of S. 

 bicipitis and related forms. This species is represented by 43 adult 

 shells, of which 17 were taken alive, and many young ones. The 

 colonies are widely separated 17 and small; living shells are rare, and 

 their collection involves the removal of much rock. The physical 

 conditions are very similar in all the stations in Buckeye and Happy 

 Camp Canyons. All the stations are on steep well-drained slopes 

 facing northward, the earth very dry (in November), even under a 

 couple of feet of rock, and scantily protected by low scrubby oak 

 brush. At Nine-mile Water-hole the conditions are quite different 

 as noted below. 



In the type locality, Station 1 (pi. I, figs. 1, 2, 3, and pi. Ill, fig. 7), 

 we took 7 living adult and 6 young specimens measuring as follows : 



Alt 14 8 14.2 14 13 13 13 12.2 mm. 



Diam 24 23.3 23 22 22 21 20.2 mm. 



This station is high on the steep south side of the canyon. 

 In a lot of 23 from Station 3 (No. 94,326), 7 are adult living shells, 

 measuring : 



17 This must be understood in a comparative sense, as indicating that many 

 apparently suitable situations examined were found barren. Doubtless a 

 longer search would show that a large number of small colonies exist. We 

 worked two days in Buckeye and several hours in Nine-mile. 



