GASTROCOPTA, NORTH AMERICA, WEST INDIES. 19 



far apart ; lamellae and plicae : parieto-angular, not or slightly 

 connecting with the peristome, spur small ; columellar rather 

 as in typical armifera, but smaller, slighter; inferior colu- 

 mellar [basal fold] tooth-like, placed obliquely, more constant 

 than in other forms as to size, shape and position; lower 

 palatal regular but slight, often rather short; suprapalatal 

 rather constant. 



"Alt. 3.3 to 3.8, rarely 4 to 4.2, diam 1.9 to 2.2 mm.; some 

 specimens are low, almost globular, alt. 3.2, diam. 2.1 mm. 



' ' Numerous specimens seen from Bismarck, North Dakota ; 

 Eastport, Iowa (Missouri River drift) ; Lincoln, Nebraska; 

 Nickerson, Kansas" (Sterki). 



This is a common shell in North and South Dakota, also in 

 eastern Colorado (Trinidad, Pilsbry}, and southward to near 

 Las Vegas, New Mexico (rocky ledges along the Gallinas 

 River, Cockerell) , Val Verde Co., Texas, in drift of the Pecos 

 River, near the High Bridge (Pilsbry and Ferriss), and to 

 Caddo Parish, Louisiana (C. B. Moore). It can be more 

 easily identified than the preceding forms, by the quite short 

 lobe of the columellar lamella (pi. 2, fig. 3), placed low on 

 the pillar, its ascending limb very low, and by the usually 

 larger development of the basal tubercle (inferior columellar 

 of Sterki). The columellar lamella has a short forward 

 branch, as in typical armifera, and in shape approximates to 

 the contracta type more than in other subspecies of armifera. 



\e. G. ARMIFERA RuiDOSENSis Cockerell. PL 1, figs. 10, 11. 



The teeth are more massive than in the typical or any of 

 the preceding forms, making the orifice much narrower. 

 Columellar lamella large and thick, having a triangular out- 

 line as seen from the back (pi. 1, fig. 11), the highest part 

 being the receding lower lobe. Length 4, diam. above aper- 

 ture 2 mm. 



New Mexico: BlackwelTs ranch, Ruidoso, the type (no. 

 73944, A. N. S. P.) from an anthill (C. M. Barber). Also 

 Gallinas canyon (T. D. A. Cockerell). 



Bifidaria armifera var. nov. ruidosensis COCKERELL, Nau- 

 tilus, XIII, July, 1899, p. 36. 



