GASTROCOPTA, NORTH AMERICA, WEST INDIES. 67 



from stream debris. The type specimen is identical in form 

 with figs. 1 and 2. Some specimens are longer (fig. 3). G. p. 

 mcclungi is separated from G. p. duplicate chiefly by the 

 character of the lip, as the shape and size of the shell are 

 variable. 



Examples have been examined from the following places; 

 all except the type lot in coll. A. N. S. P. : 



South Dakota : Indian Creek, Pennington Co. ; White River, 

 Washington Co. ; Chamberlain, Brule Co. ; mouth Vermillion 

 River, Clay Co. ; all collected by W. H. Over. 



Kansas: Lawrence (G. D. Hanna) ; pleistocene of Prairie 

 Dog Creek, Phillips Co. (Johnston; type, no. 226395 U. S. 

 N. M.). 



Colorado: Trinidad (Pilsbry) ; Pike's Peak (E. Hall). 



Arkansas: Rogers, Benton Co. (Pilsbry and Ferriss). 



Texas: New Braunfels (Ferriss and Pilsbry); Laredo 

 (Orcutt). 



New Mexico: around Las Vegas and Mesilla (Cockerell) ; 

 Albuquerque (Pilsbry and Ferriss) ; Santa Fe (Ashmun) ; 

 Mimbres River near Swartz and near Deming (Pilsbry and 

 Ferriss). 



Arizona: Holbrook (Ashmun). 



Many of the shells from New Mexico and Arizona could 

 about as well be referred to typical procera as to mcclungi. 

 The structure of the angulo-parietal lamella is intermediate, 

 rarely so distinctly forked in front as in typical mcclungi, 

 yet showing some trace of that structure, and sometimes dis- 

 tinctly. The nodule below the columellar lamella is lower 

 than in typical mcclungi, yet equal to that of many indi- 

 viduals from Dakota and Kansas. In size the New-Mexican 

 shells run from the ordinary length of mcclungi to that of the 

 largest procera; two shells, the largest and smallest noticed 

 in a large lot from near Deming, N. M., measure : 



Length 3, diam. above aperture 1.1 mm. 



Length 2.3, diam. above aperture 1 mm. 



Small specimens of mcclungi are very similar to the An- 

 tillean G. barbadensis. The lower palatal plica, however, is 

 placed more deeply in the throat in mcclungi. 



Specimens from Rogers, Benton Co., Arkansas (pi. 13, figs. 

 4, 5) have the teeth more strongly developed than any seen 



