70 GASTROCOPTA, NORTH AMERICA, WEST INDIES. 



6 teeth. The angulo-parietal is distinctly bifid in a front 

 view, slightly sinuous, but not forked in front; the infra- 

 parietal is a small tubercle, often very small, and wanting in 

 many individuals (which are perhaps not completely adult). 

 Columellar lamella is strong, transverse, a low callous (or a 

 low tooth) below it. Upper palatal plica short, the lower 

 long and entering deeply, but not quite so deeply immersed 

 as a whole, as in G. procera. Basal plica shorter, entering. 

 The peristome is expanded, thin at the edge, but having a 

 thin callous rim within. 



Length 2.55, diam. 1.15 mm. 



Distribution. Texas : lower Rio Grande valley, in river 

 debris at Hidalgo (J. A. Singley) and Brownsville. Mexico: 

 Panuco River valley, at Tampico, Tamaulipas; falls below 

 Valles and canyon below Las Canoas, San Luis Potosi (A. A. 

 Hinkley ) . 



Pupa - - STERKI, Nautilus, iv, 1891, p. 142. P. rio- 



grandensis STERKI, Nautilus, vi, 1892, p. 4 (Hidalgo, Texas; 

 no description). B[ifidaria] riograndensis Sterki, PILSBRY 

 and VANATTA, Proc. A. N. S. Phila., 1900, p. 596. 



This species tapers a little more than G. procera, the whorls 

 are more convex, and the lip-callous is thin, not nearly so 

 heavy as in procera and its subspecies. The infraparietal 

 tubercle is lacking in so great a proportion of the specimens 

 which are otherwise adult that it cannot be depended upon 

 for identifying the species. 



It stands very close to G. servilis Old., but differs by having 

 a strong, narrow crest behind the outer lip, while in servilis a 

 crest is completely wanting. Also, when typically developed, 

 the lip is a little thickened in riograndensis, and an infra- 

 parietal tooth may be present. The crest behind the lip dis- 

 tinguishes riograndensis from the Ecuadorian G. wolfiii, which 

 is otherwise very similar. 



The figured type is no. 60137 A. N. S. P., from Hidalgo, 

 Texas. 



21. GASTROCOPTA SERVILIS (Gould). PL 14, figs. 4, 5, 6, 7. 

 ' ' Shell elongated ; tapering to a somewhat acute apex, of a 



