Casey — Notes on the Pleurotomidae. 149 
to be paucispiral, but the drawing shows a multispiral proto- 
conch; this is, however, a matter of minor importance. The 
anal sinus is broad, sometimes very feeble and always median 
in position on the spire whorls though not identified with 
any particular one or more of the subequal and rather coarse 
flat spirals. The beak hasno external oblique tumidity. There 
can be but little doubt, in view of geographical variations and 
wide distribution of this genus, that Hndiatoma, of Cossmann, 
should be regarded as a synonym or as constituting a slightly 
differentiated section of Asthenotoma. The American species 
known to me may be recognized as follows, the characters of 
tecana and shalert being taken from accurate drawings and 
descriptions. They are all peculiar to the Lower Claiborne 
Eocene : — 
Concavity below the subsutural carina large, extending very nearly to the 
middle of the whorl, the surface thence to the lower margin having 
three to four equal and widely spaced spiral lines; spire almost twice as 
long as the aperture and canal combined. Length of a specimen of 9 
body whorls, 18 mm, Texas............-ceccessoeeesses.texana Gabb 
Concavity below the subsutural carina very SHOLt........esseeeereseseee 2 
2 — The concavity much longer than the intervals separating the four or five 
Spiral lyrae below it; spire rather rapidly acuminate, apparently not 
more than one-half longer than the aperture and canal together; form 
unusually stout; columella straight. Type defective but probably 
representing a specimen of about 8 body whorls, having a length of 
Pepe OOUMIAERH Sates vorniare oloe ge tclae sinsle eam clteteeta nian sie aves shaleri Vgn. 
The concavity not longer than the intervals separating the large lyrae below 
the middle of the whorls ........ Go OoOn Cetoas panddeoodanes0c aoopaucos 3 
3— Form somewhat as in the preceding species, the spire rapidly tapering 
and not more than one-half longer than the aperture and canal com- 
bined, the inner outline of the columella broadly, evenly arcuate; 
spire whorls with a strong flattened subsutural lyra, bordered beneath 
by a feeble concavity not longer than a seventh or eighth of the total 
length of the whorl, succeeded by two smaller and more approximate 
carinules and these by four strong lyrae occupying the entire space 
thence to the lower margin; on the larger whorls there is a single 
small raised line alternating with the last-named lyrae. The obtuse 
ribs of the nepionic whorls are few in number and become completely 
obsolete on the fourth or fifth whorl. Length of a specimen of 7 body 
whorls, 12 mm.; width, 3.4mm. Texas (6 miles south of Wheelock) — 
Wit, Ate isl, AUN Sboaoodbon dang ppOGeCUaCG GO0b doc OCOUDS eximia n. sp. 
Form very much elongated, the spire apparently more than twice as long as 
the aperture and canal combined, gradually, evenly acuminate; colum- 
ella somewhat obliquely tumid; spire whorls each with a very coarse 
