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 lamelle rather 
short and almost simple; palatals near the margin.” (Sterki.) 
94. Bifidaria pentodon Say, pl. 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. 68. 
BIFIDARIA PENTODON Say. (Binney, Fig. 347.) 
white; whorls five, convex, regularly increasing in size, the lasta 
little swollen and slightly impressed behind the 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 ona 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). 
