Casey — Notes on the Pleurotomidae. 157 
throughout is very nearly as in elegans but with larger and stronger ribs. 
Length of the embryo and first three spire whorls, 2.7 mm.;, width, 1.5 
mm. Lower Claiborne Eocene of St. Maurice, La........-acuta n. sp. 
Embryo larger and much stouter than in acuta, fully as wide as high, acutely 
pointed, the nucleal tip being small and rather elevated, the whorls four 
in number, closely coiled, feebly convex, all highly polished and devoid 
of sculpture, the lowermost only acquiring a few riblets in its last quad- 
rant, which riblets merge gradually into the ten or eleven ribs of the 
body whorls; lyrae and fasciolar surface nearly as in the two preceding 
species. Length of a specimen consisting of the embryo and one com- 
plete body whorl, 1.9 mm.; width, 1.0 mm. Lower Claiborne Eocene of 
St. Maurice, Las. je. cath ove denkos sc decaheiciasscses scsscO0NOlOta D. Sp, 
The species described by Harris under the names vaughani 
and sylvaerupis also belong to this genus, but, besides differ- 
ing from those of the table to some extent in the form of the 
embryo, have the ribs less numerous and relatively larger; 
the Upper Claiborne bauwmonti may likewise be included as a 
slightly aberrant or degenerate member. A considerable num- 
ber of specimens of elegans were obtained, but none with 
more than two body whorls, and it is probable that it may 
really be a small species when mature; in this case it would 
contrast greatly with vaughani and sylvaerupis, which are 
moderately large species with a many-whorled spire. 
Leptosurcula n. gen. 
In this genus the form is very slender, fusiform, the canal 
very long, the aperture and canal together being about half as 
long as the entire shell. The embryo is relatively very large, 
higher than wide, conicaland composed of five or six polished 
whorls, the lower whorls gradually acquiring close-set longi- 
tudinal riblets, and then, equally gradually, the spiral lyrae. 
The type is the very isolated P. beadata * Harris, of the Texas 
* The name ‘‘ beadata’’ is of an etymology difficult to ascertain. If it 
is derived from the English word dead, referring to the beaded subsutural 
collar, it is indeed a ‘‘ barbarism,”’ or, at any rate, a procedure in the forma- 
tion of specific names which is generallycondemned. It is, however, per- 
haps not so much worse than mortoniopsis and texanopsis —Latin and 
Greek hybrids which have been used by two of our authors,— or such 
words as texacona, texagyra, texacola and texalta, which have been employed 
by Prof. Harris. 
