238 THE CHICAGO ACADEMY OF SCIENCES. 



base, but with relatively larger horizontal part, the bifurcation 

 of the parietal and the presence of a supra-palatal" (on the up- 

 per part of the outer lip) "the last just as it is in B. armifera" 

 The species is very rare and is confined to the western region. 



SECTION VERTIGOPSIS (Cockerell) Sterki. 



"Shell small, vertigo-like, albino; parietal lamellae rather 

 short and almost simple; palatals near the margin." (Sterki.) 



94. Bifidaria pentodon Say, pi. xxx, fig. 12. 



Pupa pentodon SAY, Journ. Phil. Acad., Vol. II, p. 476, 1822. 



Pupa tappaniana ADAMS, Silliman's Journal, ed. i, Vol. XL, Suppl. 



Shells of Ver., p. 158, 1842. 

 Pupa pentodon curta STERKI, Land and F. W.Moll., New Phil., Ohio, 



1894. (Variety.) 

 Pupa montanella CKLL., MSS., PILSBRY, The Nautilus, Vol. XI, p. 118, 



1898. 



Shell: Elongately ovate, shining, minutely umbilicated; 

 growth lines minute, oblique; apex smooth; color spermaceti- 



Fig. 

 BIFIDARIA PENTODON Say. (Binney, Fig. 347.) 



white; whorls five, convex, regularly increasing in size, the last a 

 little swollen and slightly impressed behindthe peristome; apex 

 obtusely pointed; sutures well impressed; aperture rounded or 

 semicircular, scarcely oblique, eight-dentate as follows: asingle, 

 rather long, cylindrical tooth on the parietal wall, which is al- 

 most straight and directed toward the base; a small, conical 

 tubercle on the columella; three small, conical tubercles on the 

 base of the aperture, two small tubercles placed squarely on 

 the base, and one, longer and narrow, placed on the turn of 

 the outer lip; three small, conical tubercles on the outer lip 

 (palatal), the upper and lower being very small and the cen- 

 tral tubercle longer; one or more of these smaller tubercles 

 may be wanting; all of the teeth are placed on a ridge of callus 

 which encircles the inner surface of the aperture; peristome 

 somewhat reflected, sharp, the terminations separated but con- 

 nected by a thin callus; umbilicus very minutely perforated; 

 base of shell rounded (Fig. 68). 



