544 PROCEEDINGS OF THE ACADEMY OF [DeC, 



within the State of Missouri. The type specimen measures alt. 6.2, 

 diam. 11.25 mm., with 5 whorls. The outer hp-tooth recedes a little 

 and is somewhat broad and rounded. The lower or basal tooth is 

 marginal, decidedly narrower than its fellow, and tubercular. The 

 notch between the two teeth is squarish and decidedly wider than deep. 

 See PI. XXII, fig. 1. 



In the stony ravines of the Ozark system at Chadwick, Mo., the 

 extensive series collected shows two forms, which we will call 1 and 2, 

 occurring in the proportion of 13 of form 1 to 38 of form 2, or one to 

 three. Form 1 (PI. XXII, figs. 2, 3) is nearly typical, but more frequently 

 the outer tooth is as small as the basal. The size varies from 5.2 x 10 

 to 7.3 X 12 mm. Form 2 is more solid, with the aperture more con- 

 tracted by larger teeth (PI. XXII, figs. 4-6). The two lip-teeth are 

 subequal, the basal one massive and broadly conic. The notch between 

 them is narrower than in the type, and as deep as it is wide. No speci- 

 mens reach the size of form No. 1, the extremes measuring 5x9 and 

 5.3 X 10 mm. Whether these two forms occurred together or in sepa- 

 rate colonies was not noted. 



The forms from other localities mentioned above vary from typical 

 to a condition of teeth intermediate between the two forms described. 

 Thus at Wyandotte, near the northeast angle of Indian Territory, 

 intermediate specimens occur in profusion (PL XXII, figs. 7, 8). 

 Among them was a mutation with the basal tooth obsolete, singularly 

 like P. smithi Clapp, except in the smaller size, diam. 10.4 mm. (fig. 9). 



On the northern side of the cliff defining the summit plateau of 

 Magazine Mountain it occiurs adjacent to the locality for P. edentata 

 magazinensis, though not actually associated with it. The specimens 

 here are mostly small, diam. 9.5 to 11.2 mm. On the drier and warm 

 side south of the summit plateau and in the valley south of Blue Moun- 

 tain Station, at the southern foot of the mountain, they are equally 

 small. The largest inflecta we found were taken in the Petit Jean 

 Mountains, about ten miles south of Magazine Mountain, where they 

 measured 12.3 to 13.8 mm. diam., and usually have the basal lip 

 calloused on the axial side of the basal tooth. The crest behind the 

 lip is also sharp and high. 



Polygyra inflecta media PUs. PI. XXII, fig. 10. 



Pilsbry, Proc. A. N. S. Phila., 1903, 197, in text. 

 Lip-teeth reduced to small tubercles, but still stronger than in P. 

 edentata. Seligman, Barry Co., Mo. (Ferriss, 1901). Types No. 

 81 437 A. N. S. P., cotypes in Ferriss Coll. 



