1915.] NATURAL SCIENCES OF PHILADELPHIA. 377 



Station 15 (further east on the same branch, a little higher). 

 Rather stout shells, with the mouth built out shortly (nearly 1 mm.) ; 

 about 15 ribs; lamellae one or two. 12x4 mm. 



Station 13 (eastern peak of the rim of Tweed Canyon). Fine- 

 ribbed, like PI. XIV, figs. 5, 5a. 



Station 11 (steep, stony, arid, southern slope of ridge projecting 

 into amphitheatre, vegetation xerophytic). The shells are greater 

 in diameter than the types, very uniform in sculpture, having 16 or 

 17 ribs on the penultimate whorl, the peristome built forward further 

 than usual in the type lot. 10.5 x 3.7 mm. axial or axial and superior 

 lamellae. 



Another lot, taken a couple of hundred feet higher, are similar 

 in form, sculpture and lamellae; ribs 15 to 19. 



Station 12 (peak on eastern rim of amphitheatre). The shells 

 are larger than at the preceding stations, with more ribs, 26 to 28 

 on the penultimate whorl. Half of those opened have one, half 

 two lamellae, the superior lamella not very strong. These shells 

 are like those from Station 4 and 5. See PI. XIV, figs. 4 to 46. 



Length 13.7, diam. 4.2 mm.; whorls 13. 

 12, " 4 '' " llf. 



Station 40 (between crest and foothills, north end of the range). 

 Stout, rather large shells, with a strongly developed columellar lamella 

 only in several opened. 37 to 43 ribs, nearly or quite as wide as 

 their intervals. (PI. XIV, figs. 5, 5a). 



Length 12.3, diam. 4 mm. 

 10.5, " 4.1 " 



These shells have more ribs than any other colony of H. danielsi, 

 and they may be referable to H. campestris cochisei. The shells are, 

 however, larger than the latter, some of the ribs are broken down, 

 as in danielsi, and the locality is distant from other known colonies 

 of H. c. cochisei. Only a very small lot was taken, and, pending 

 further collections, its identity may be left undecided. 



Station 39 (between crest and foothills at north end of the range). 

 Much larger than the typical form, stouter, with few, strong and 

 widely separated ribs. Only the axial lamella developed. (PL 

 XIV, figs. 2 to 2c). 



Length 13.3, diam. 4.8 mm.; whorls 13; ribs 15. 



