GASTROPODA. 889 
Bucania lindsleyi.] 
the slit shorter, than usual. Hight of shell 12 mm.; width of aperture 12 mm.; hight 
ofsame about 6 mm.; width of umbilicus 6.5 mm.; width of inner end of last volution 
about 4.7 mm. 
The form is more globose and the umbilicus relatively smaller than in any of 
the preceding species of the genus. In both of these aspects it reminds one strongly 
of B. sulcatina, of which it is probably a dwarfed descendant. 
Formation and locality—The types are from the upper part of the Trenton group, near Burgin, Ky. 
A cast of the interior, agreeing in every respect with the type, was found in the Ctenodonta bed of the 
Black River group, near Fountain, Minnesota; another (fig. 19) is from the Stones River group, at Minne- 
apolis. A very small specimen, presumably of the same species, occurred in the Fusispira bed at Wykoff. 
Collection.—H. O. Ulrich. 
e 
Bucania LINDSLEYI Safford. 
PLATE LXVI, FIGS, 24 and 25. 
Bellerophon lindsleyi SAFFORD, 1869, Geol. of Tenn., pl. G@, figs. 3a, b,dande. (8¢ doubtful.) Not 
described. 
Shell 30 mm. to 40 mm. in hight, the width of the aperture slightly less than 
the greatest hight of shell; volutions about three, embracing less than a fourth of 
the next within, rounded on the back, somewhat semi-circular in cross-section, 
narrowly rounded beneath the middle line of the sides; umbilicus moderately steep, 
of large size considering the rapid expansion of the volutions, its greatest width 
equalling about one-third of the hight of the shell; aperture somewhat expanded in 
the lower part, semi-elliptical in outline, the lateral angles narrowly rounded and 
scarcely reflected, the center of the lower outline very slightly indented by the 
preceding whorl; lower lip entire, thickened inwardly; upper or outer lip thin, 
the margin sweeping backward to form a broad shallow sinus, the center continuing 
backward as a narrow slit, the latter having a length of at least 10 mm. in a speci- 
men 38 mm. in hight. Surface coarsely lamellose, the lamelle, which indicate the 
margin of the aperture at previous stages, occurring at intervals on the back of the 
last volution varying from less than 2 mm. to 4mm. or more, the average being 
about 3mm. Usually the lamelle are crossed approximately at right angles by 
more or less unequal and irregular ribs, seven to ten in the space of 5 mm., and 
these again by fine lines of growth. Often the ribs are irregularly broken up and 
sometimes they combine to form an obscure network reminding one of the surface 
sculpture of B. punctifrons Emmons. (See pl. LXVII, fig. 44). Slit-band distinct, 
slightly concave, margined on each side by a sharply elevated, thin line; lunule 
somewhat unequal but always clearly defined, rather crowded. 
This fine shell is readily distinguished from all of the preceding species of the 
genus by the rapid expansion of its whorls. 
