294 PROCEEDINGS OF THE ACADEMY OF [Nov.-Dac, 



Sonorella hestema n. sp. PI. IV, figs. 6, 6a, 66. 



A long series of dead shells was taken at Station 148 (1917) in a 

 rock slide on the south side of the Tucson-Benson highway, near the 

 cave on Shaw's ranch, southern foothills of the Rincons, at about 

 3,500 feet. They are smaller and more solid than S. rinconensis, 

 and the umbilicus is somewhat smaller. It is more depressed and 

 has a wider umbilicus than S. sabinoensis. In color and surface it 

 resembles the latter species. The freshest shells are between cinnamon 

 and tawny-olive, fading around the umbilicus, white on both sides of 

 the chestnut-brown band. The suture descends rather abruptly to 

 the aperture, but not quite so deeply as in *S. hachitana. 



Alt. 13.5, diam. 22.4 mm. (type). 

 " 14.7, " 25.9 " 



In a series of 37 adult examples, the smallest measures 20.1 mm. 

 in diameter, the largest 25.9 mm. They run as follows: 



Diam. 20-20.9 mm., 4 specimens. 



The station is an extremely arid one. It is a true desert Sonorella. 

 The status of the form is uncertain, but it can scarcely be linked with 

 any of the Santa Catalina or Rincon species, so that, while we do 

 not like to describe a Sonorella without examination of the soft 

 anatomy, there seems nothing else to do in this case. Its status 

 may be revised when living examples come to hand. 



Sonorella marmorarius n. sp. PI. Ill, figs. 0, 9a, 9b. 



The shell is depressed, rather solid, umbilicate (the width of um- 

 bihcus contained about 7 times in that of the shell, suddenly widening 

 at the last whorl to about double its former width); light pinkish 

 cinnamon, paler around the umbilicus, and whitish on both sides 

 of the chestnut-brown band above the periphery. The surface is 

 glossy. Embryonic shell oi IY2 whorls, the last of which is densely, 

 irregularly granular, with indistinct protractive and retractive 

 threads (when unworn), subsequent whorls delicately marked with 

 growth-lines, and under the lens showing some weak spiral impressed 

 lines in places on the upper surface of the last whorl. The suture 

 descends rather deeply in front. Aperture is quite oblique, oval. 

 Peristome expanded throughout, with a gray edge, somewhat 

 thickened within, the margins generally connected by a roughened 

 callous ridge in fully adult shells. 



