18 GASTROCOPTA, NORTH AMERICA, WEST INDIES. 



Ic. Form affims Sterki. PL 1, fig. 5. 



"Somewhat small and slight; near similis, but less cylin- 

 drical, rather somewhat oblong; whorls 6-6%, somewhat 

 more convex than in similis, the last rounded at the base and 

 little flattened over the palate, with none or a slight scar 

 over the lower palatal plica; aperture somewhat rounded, 

 peristome never continuous; parie to- angular lamella well 

 connected with the peristome, spur of the parietal larger 

 than in typical armifera; columellar nearly axial, a broad 

 lamella, reaching down to the base, with distinct lines of 

 growth, visible from the outside through the (fresh) shell 

 below the umbilicus, as in B. contract a; inferior columellar 

 [basal fold] wanting or small; lower palatal quite short, or 

 even a transverse, short, abrupt lamella. Alt. 3.5 to 4, diam. 

 2.2 to 3 mm. 



"Distribution: Northern Ohio, Michigan, Indiana to Min- 

 nesota and Kansas; seems rather scarce in the first-named 

 states, common in Kansas. Found on sandy dunes on Lake 

 Erie in Ohio. 



"It is notable and significant that both the columellar and 

 the lower palatal in this form are of the same shape as in B. 

 contracta, while in typical armifera they are quite different, 

 yet the latter shows a tendency to having the peristome con- 

 tinuous, while in affinis its ends are always apart" (Sterki). 



The lobe of the columellar lamella is rather thin, abrupt 

 above, and the forward branch is almost obsolete. Difficult 

 to distinguish from the typical form and form similis. Fig- 

 ured from a paratype. 



\d. G. ARMIFERA ABBREViATA (Sterki). PL 2, figs. 1, 2, 3. 



"Averaging rather small, slight, somewhat fusiform to 

 ovate or cylindro-conical ; apex low, conical or rounded; 

 whorls only 51/2-6 (rarely 6%), little convex, with the penul- 

 timate comparatively broader than in the other forms, the 

 last rounded at the base, slightly flattened over the palate; 

 color somewhat milky-whitish; surface with a dullish gloss, 

 strias fine and slight; aperture somewhat small; peristome 

 moderately everted, its ends (in most forms) comparatively 



