150 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
only two specimens in the collection have the outer lip fractured, and I 
am therefore unable to pronounce conclusively upon the presence of a 
true notch. 
PLEUROTOMA VENUSTA, 0D. Sp. 
Plate, fig. 2. 
Slender, acuminate; whorls about nine, convex, ornamented by numer- 
ous fine revolving lines, which on the body-whorl are disposed in pairs; 
one deeply impressed line margins the majority of the volutions imme- 
diately below the suture; sinnated lines of growth not prominent; spire 
and aperture of about equal length. ; 
Length, 14 inch. (No. 1509.) 
Jackson, Miss. 
PLEUROTOMA PLATYSOMA, I. sp. 
Plate, fig. 3. 
Whorls ? in number, flattened, each volution following the other al- 
most in direct continuation without any prominent sutural division, and 
ornamented with numerous revolving lines, which on the caudal portion 
of the body-whorl tend to alternate, a fine line interposing itself between 
the more prominent ones; aperture probably a little more than one-third 
the length of the entire shell; notch deep, sigmoidal. 
Length, 2 inches? (No. 8916.) 
Atascosa County, Texas. 
EUCHEILODON, Gabb. 
EUCHEILODON CRENO-CARINATA, 0. Sp. 
Plate, fig. 4. 
Whorls subsealariform, flattened above, the angulation formed by a 
doubly crenulated carina; volutions ornamented by numerous revolving, 
profoundly elevated striz, which are decussated by the much finer sinu- 
ated lines of growth; the upper or flattened portion with a prominent 
\ 
beaded line bordering the suture, and two (a finer and a coarser line) © 
intermediate ones between the same and the carina; outer lip grooved 
within, and probably sharply crenulated by the terminations of the re- 
volving strie; columella with about eleven beads, which decrease in 
size from above downwards. Aperture nearly equal in length to the 
spire? 
Length of fragment, 1 inch. (No. 8921.) 
Jackson, Miss. 
SCALARIA, Lam. 
SCALARIA UNILINEATA, 0. Sp. 
Plate, fig. 5. 
Whorls about nine in number, convex, with numerous very faint, 
almost invisible, revolving lines, and much more prominent transverse 
