1910.] NATURAL SCIENCES OF PHILADELPHIA. 119 



flattened and tapering to the base, which is a little gibbons and rounded. 

 Its latter part is straightened and runs forward shortly beyond the 

 preceding whorl, the upper wall descending slightly. Otherwise it is 

 not noticeably contracted behind the aperture. The outer lip is 

 narrowly expanded and revolute, and is lined within with a rather 

 thin white callus. 



One living specimen in the lot is an albino, pure white with some 

 bluish spots. 



The axial lamella is strongly developed; superior lamella variable, 

 but usually strong and extending through the last half of the penultimate 

 whorl. Basal lamella variable, usually wanting, but sometimes strong. 

 Twenty specimens opened give the following data: 



Three lamellae: superior, axial and basal (15%) — 



Length 14, diam. 4 mm. ; whorls 12^. 

 14, " 4 " " 12f. 



13.5, " 4 " " 12^ 



Two lamellae: superior and axial (65%) — 

 Length 14.8, diam. 4 mm.; whorls 13i. 



One lamella: axial (20%)— 



Length 12, diam. 3 . 8 mm. ; whorls 1 H. 



11.8, " 3.8 " " Hi 



11.3, " 3.8 " " Hi 

 f « 4 " " (spire broken). 



The above specimens were taken at random. 

 Holospira arizonensis emigrans n. subsp. PI. XI. figs. 5-8. 



The shell is in the average more slender than arizonensis, with more 

 numerous whorls ; striation slightly finer, and often extending weakly 

 upon the smoother lower whorls; the last whorl has abroad contraction 



