GASTEROPODA OP THE LOWER GREEN MARLS. 161 



Genus CINULIA Grey. 

 CiNULiA (Oligoptycha) naticoides. 

 Plate XIX, Figs. 28-30. 



ActcBonina naticoides Gabb: Jour. Acad. Nat. Sci., Phila., 2d ser., vol. 4, p. 299, 

 PL XVIII, Fig. 2; Meek, Geol. N. J., Newark, 1868, p. 728. 



Solidula naticoides Gabb : Synopsis, p. 38. 



Cinulia (f) 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, neai-ly 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. Grabb to possess "two plates," but upon 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 Actceon 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 



