GASTEROPODA OF THE LOWER GREEN MARLS. 161 
Genus CINULIA Grey. 
CINULIA (OLIGOPTYCHA) NATICOIDES. 
Plate x1x, Figs. 28-30. 
Acteonina naticoides Gabb: Jour. Acad. Nat. Sci., Phila., 2d ser., vol. 4, p. 299, 
Pl. xvi, Fig. 2; Meek, Geol. N. J.,. Newark, 1868, p. 728. 
Solidula naticoides Gabb: Synopsis, p. 38. 
Cinulia (?) naticoides (Gabb) Meek: Meek, Check List Cret. and Jur. Foss., p. 16; 
Stoliczka Ind. Geol. Surv., Pal. Indica, Cret. Fauna South. Ind., vol. 2, p. 411. 
Shell small, less than half an inch in height; globular in outline and 
consisting of about three volutions. Spire low, nearly conforming to the 
rotundity of the body volution; columella short, axis imperforate in the 
shell, aperture ovate, moderately large, widest below, about two-thirds as 
high as the body volution; outer lip thickened and strongly crenulate within. 
Columellar lip said by Mr. Gabb to possess ‘two plates,” but wpon the casts 
before me I can not find evidence of more than a single one, and that one 
projects horizontally to a considerable distance from the columella. Surface 
of the shell marked by closely arranged, spiral lines, of which twenty-eight 
to thirty may be counted on the body volution. These lines on the cast 
are rounded, elevated ribs, separated by equally wide concave grooves. 
This is a remarkably pretty species even in the condition of internal 
casts, the only state of preservation in which I have seen it. It somewhat 
resembles Acte@on concinnus H. & M., from the Upper Missouri Cretaceous, 
but is very much larger than any of that species which I have seen, and 
has the mouth very much wider in proportion. The surface of this shell 
may have had the lines punctured as in that one, but there is no distinct 
evidence of it on the several casts examined; although there is a tendency 
to a crenulation of the ridges, which appears to have been caused by trans- 
verse lines of growth parallel to the margin of the aperture. It corresponds 
very much more closely to A. concinnus M. & H. than Mr. Gabb supposed, 
as it has but one tooth, instead of two as he stated, unless he had a different 
species in hand, which is scarcely possible. Most of these casts show only 
a slight ridge in place of the tooth, but a single cast, figured, shows the 
cavity unmistakably. 
MON. XVIII——11 
