1910.] 



NATURAL SCIENCES OF PHILADELPHIA. 



25 



The Cincinnati Series. 



Say did not give the locality of his type of albolabris nor its height. 

 Its width is given as one inch. W. G. Binney (Manual Am. Land 

 Shells, p. 299) gives 30 x 17 mm. as the size of typical albolabris, 

 but gives no information as to the basis on which the measurement 

 was determined. 



In the absence of any better basis for comparison, the Cincinnati 

 series was adopted as probably representative of the species in the 

 Ohio Valley and a locality about midway between the northern and 

 southern range of the typical form. 



/6 



/S 



II -t 20 ± Z/ i. ZZ,?>w<s^ 



Fig. 2 — Heights — 152 Cincinnati. 



The Cincinnati shells exhibit considerable variation in height, but 

 within comparatively narrow limits, ranging from 16 to 22 mm., the 

 average being 18.78. The major mode is at 18.75, with minor modes 

 at 17, 18, 20 and 21. It is to be noted that practically one-half (75) 

 of the specimens are from 18 to 19 mm. in height. 



i 1.6 



23 ± . 2f ± 30 £ 3/ i 32 i; fit* 



Fig. 3— Widths— 152 Cincinnati. 



