66 GASTROCOPTA, NORTH AMERICA, WEST INDIES. 



Medina Co.; Devil's River, Val Verde Co. (Pilsbry and 

 Ferriss) . 



Nearly all of the specimens seen are from stream debris, 

 though many are so fresh that it is not likely they had floated 

 far. In some lots, as that from New Braunfels, the form 

 mcclungi occurs in the same debris; but it seems probable 

 that this small, thick-lipped form lives in more arid situa- 

 tions than the larger, darker-lipped duplicata. The area of 

 mcclungi is much more extensive than that of duplicata west- 

 ward, but in the east they are nearly coincident. The rela- 

 tions of the forms can be more exactly estimated when gath- 

 erings of living specimens come to hand. 



.18c. G. procera mcclungi (Hanna & Johnston). PI. 13, figs. 

 1 to 5. 



The average size is smaller than procera or duplicata; 

 whorls typically shorter. The face of the thick lip is convex, 

 and the greatest thickness of the lip-callous is at (not within) 

 the edge of the aperture. Teeth as in duplicata, the angulo- 

 parietal lamella being bifid and forked in front (fig. 5), and 

 there is a tubercular tooth below and partially united with 

 the columellar lamella, which appears duplicated when the 

 subcolumellar portion is strongly developed, as in fig. 4. 

 There is a rather low crest behind the lip, and an external 

 impression (sometimes wanting) over the lower palatal plica. 



Length 2.03, diam. 0.96 mm. ; length 2.07 and 2.44, diam. 

 1 mm. (Hanna and Johnston). 



Length 2.26, diam. 1.08 mm.; fully 5 whorls (fig. 1, Clay 

 Co., N. D.). 



South Dakota to the Eio Grande, Texas; west to eastern 

 Colorado, the Rio Grande and Mimbres valleys, New Mexico, 

 and Holbrook, Arizona. Type locality, pleistocene of Prairie 

 Dog Creek, Phillips Co., Kansas. 



Bifidaria mcclungi HANNA and JOHNSTON, Kansas Univer- 

 sity Science Bulletin, vii, no. 3, Jan. 1913, p. 119, pi. 18, f. 1, 2. 



A subspecies of the semi-arid country, now probably ex- 

 tinct over much of its former territory, the limits of which 

 are indicated above. Nearly all of the specimens known are 



