146 STREPTOSTYLA. 



5a. S. IRRIGUA var. CINGULATA C. & F. Vol. I, p. 45. 

 56. S. IRRIGUA var. VENTRICOSA Martens. Biologia, p. 93. 

 5c. S. IRRIGUA var. SIMILIS Strebel. Vol. I, p. 45. 



5d. S. IRRIGUA var. QUIROZI Strebel. Vol. I, p. 44. (Spiraxis 

 bullacea Pfr., Malak. Bl., xiii, 1866, p. 84, is a very 

 young state of this species, according to von Martens, 

 Biologia, p. 93, pi. 5, f. 11.) 



6. S. SHUTTLEWORTHI (Pfr.). Vol. I, p. 44. 



7. S. POTOSIANA Dall. PL 29, fig. 67. 



"Shell moderately large and solid, opaque white with a 

 brilliantly polished translucent yellowish-olive periostracum, 

 with occasional darker zones axially arranged; the periostra- 

 cum after the death of the animal rapidly peels off, leaving 

 the surface white and smooth; whorls in the adult seven, 

 smooth, not wrinkled axially in front of the very distinct 

 suture; spire rather blunt, the whorls between the sutures 

 convex; sides of the last whorl somewhat parallel, apex and 

 base of the shell about equally tapering; outer lip sharp, 

 slightly sinuous; the aperture narrow behind and rather wide 

 in front, the axis and pillar twisted as usual in the genus. 

 Length of shell 40, of aperture 28, of last whorl 34 mm. ; 

 max. diameter 15.5 mm." (Dall). 



Mexico: Alvarez Mountains, State of San Luis Potosi, at 

 a height of 7,200 ft. (Dr. E. Palmer). 



S. potosiana DALL, Smithsonian Misc. Coll., vol. 48, p. 190, 

 pi. 44, f. 4 (July 1, 1905). 



This species is related to 8. shuttleworthi and S. novoleonis. 

 The columellar fold is less developed than in the former, and 

 the latter part of the second whorl and first half of the third 

 are much narrower. It is about twice the size of S. novo- 

 leonis, differing further by the less impressed suture, the 

 whorl sloping up to the suture, not flattened below it as in 

 novoleonis. 



8. S. PALMERI (Dall). PI. 29, fig. 68. 



"Shell small, slender, subtranslucent, with a pale, thin. 



