NATURAL SCIENCES OF PHILADELPHIA. .", 1 



rounded furrows between ; those along the middle of the ventral or outer 

 being smaller and more crowded than those toward the lateral regions ; cro 

 ing these are numerous very fine, crowded stria? of growth, which carve 

 strongly backward in passing over the periphery, parallel to the margin of 

 the very profound sinus in the lip on the ventral side.* Aperture trans- 

 versely oval. 



Greatest diameter of a mature specimen, 2-23 inches; thickness, or trans- 

 verse diameter, about one inch; dorso-ventral diameter of last turn near 

 aperture, 0-86 inch. 



Among the specimens before us there seem to be two varieties, which may 

 possibly prove to be specifically distinct. One of these, which we regard as 

 the_ typical form of the species, has the periphery very depressed-convex, 

 while in the other, this part is distinctly more convex or rounded. As they 

 agree, however, apparently almost exactly in all other characters, and both 

 forms vary somewhat in the convexity of the periphery, we are inclined to 

 view this as merely a sexual difference. In the more convex forms the lateral 

 nodes seem to be generally a little more inclined to become slightly elongated 

 in the transverse direction of the whorls, though this character appears not 

 to be entirely constant. In both forms the longitudinal or revolving surface 

 ridges and furrows become nearly or quite obsolete, toward the aperture, on 

 the outer volution. 



Internal casts of this species seem to be almost exactly like specimens 

 figured by European authorities under the name N. tubrculatus, Sowerby. As 

 that species, however, attains a much larger size, and has, according to Prof. 

 McCoy's description, a very large siphuncle, while none of the figures or de- 

 scriptions of it we have seen either show or mention the distinct longitudinal, 

 or revolving costae, so well defined on the surface of our species, we can 

 entertain no doubt in regard to its being clearly distinct. It is true the 

 figures of iV. tuberculatus alluded to all represent only internal casts, while 

 the longitudinal markings mentioned on our shell are not seen on internal 

 casts ; but it is scarcely possible that such markings would never have been 

 observed, as impressions in the matrix, if not otherwise, had they existed in 

 Sowerby's species. 



This species is named in honor of Prof. E. T. Cox, State Geologist of In- 

 diana. 



Locality and position. Three miles west of New Providence, Indiana ; from 

 a light gray, brittle limestone, of the age of the St. Louis division of the Lower 

 Carboniferous. 



Lituites Graftonensis, M. and W. 



Shell rather small, with isolated portion discoid, planorbicular, and slightly 

 concave on both sides ; volutions four or more, slightly embracing, increas- 

 ing very gradually in size, with transverse section nearly or quite circular, 

 excepting the slight concavity on the inner side. Surface ornamented 

 numerous distinct, very regularly arranged costa?, which cross the sides of 

 the volutions very obliquely backward from the inner side, curving strongly 

 backward as they approach the periphery, and after crossing the middle of 

 the same, again deflected forward as on the opposite side, thus indicating a 

 profound sinus in the outer side of the lip ; the sinus being very narrow, but 

 not exactly angular at its termination, and widening rapidly forward ; fine, 

 somewhat imbricating stria? of growth also run parallel to the costae. Septa 

 apparently moderately distant and running nearly straight across the sides. 

 Siphuncle and free part of the body chamber unknown. 



Greatest diameter of the coiled part, 2-10 inches ; transverse diameter, 0-54 

 inch ; dorso-ventral diameter of outer turn, about 0-52 inch. 



This would be the dorsal side according to the nomenclature in most general use 



1870.J 



