GASTROPODA. 891 
Bucania frankfortensis.] 
Formation and locality—Trenton group, De Kalb county, and Nashville, Tennessee. 
Collections—Prof. J. M. Safford; E. O. Ulrich. 
BucANIA FRANKFORTENSIS, 2. sp. ( Ulrich.) 
PLATE LXVI, FIGS. 30—33. 
This species is related to both Bb. lindsleyi and B. nashvillensis, but is distinguished 
from both by its subtriangular aperture, thicker inner lip and coarser surface 
sculpture. The volutions are also narrower and the hight of the shell, as compared 
to the width, relatively greater. While it is scarcely possible that any one will 
confound it with the first named, such an occurence is not improbable with the 
second, since in both the dorsum is obtusely angular. Still, where good ventral 
views can be compared (see plate LXVI, figs. 32 and 37), showing their different 
mouths and the more rapid lateral expansion of the outer volution of B. nashvillensis, 
a glance should suffice to separate them. 
Formation and locality Near top of Trenton group, Frankfort, Kentucky. 
Collection.—H. O. Ulrich. 
BUCANIA SUBANGULATA, 2”. sp. (Ulrich.) 
PLATE LXVI, FIGS. 20—23. 
In this well marked species the dorsum is obtusely angular, the slope of the 
surface from the slit-band to the edge of the umbilicus somewhat flattened, and the 
sides sharply rounded or subangular, these features imparting a widely triangular, 
perhaps it would be better to say rhomboidal, section to the volutions, which of 
itself is sufficient to distinguish the species from the associated B. rugatina. Con- 
tinuing our comparisons with that species, we find that the surface markings, 
though similar in pattern and strength, are not so regular, and the umbilicusis a little 
larger and better defined, while the slit-band forms the flat summit of a low keel 
instead of a smooth groove. Both B. frankfortensis and B. nashvillensis are probably 
closely related, though readily distinguished by their greater size, relatively smaller 
umbilicus, and more rapidly enlarging volutions. At maturity, however, the 
ventro-lateral angles are more abruptly expanded in B. subangulata, giving the 
aperture a more broadly triangular form than is the case in either of the larger 
species. It is to be borne in mind, further, that these large shells require no more 
turns to attain their full growth than do specimens of the present species less than 
half their size. 
In the largest of eight specimens the hight is about 23 mm., the width of the 
aperture about 25 mm., the hight of same (in a side view) 17 mm. In a small 
specimen the same measurements resulted respectively in 9mm., 9 mm., and 5 mm., 
