Kf'ir iSjicrics of Fossils from Ohio. 311 



Heldei'bcirg group, near the lower part, at Smith and Price's, 

 and at other (piarries near Columbus, Ohio. 



Gryroeeras sciiiinodosuni, u. sp. 



Pal. O., Vol. III. Plate 4, Fig. 5. 



Shell .small, compactly coiled, aud consisting, iu the specimeu used, of a 

 little more than two volutions, which increase rather rapidlj'' in diameter 

 Avith increased age ; they are somewhat wider transversely than in a dor.so- 

 ventral direction, and are .slightly triangularly elliptical in a transverse sec- 

 tion ; the greatest transverse diameter being very slightly outside of the 

 middle of the dorso-ventral diameter. The inner one and a half coils are 

 smooth on the exterior, but the outer volution, for a little more than the 

 larger half, is ornamented by a .single series of comparatively large, trans- 

 verse, triangularly elliptical nodes on each lateral surface, having the angular 

 side of the node placed anteriorly and the opposite side nearly straight. 

 The nodes are placed at distances from each other about equal to one-half 

 the dorso-ventral diameter of the tube at the node indicated. The septa are 

 not clearly defined and cannot be given with certainty; but they appear 

 to be distautl}^ placed on the inner portions of the shell, while on the nodose 

 portion they seem to be placed at about half the distance of the nodes apart. 

 The siphuncle has not been observed. The surface of the shell, as seen on a 

 fragment of the substance remaining on the dorsum of the outer volution, 

 is marked with rather close, distinct, revolving, lines or ridges, crossed by 

 more closely arranged transverse lines, A\iiich make a shallow retral bend 

 in crossing the back of the shell. 



The specimen is probably an immature shell, but is a distinctly 

 marked species, differing strongly in its form and nodose charac- 

 ter from any of those associated with it. It most nearly resem- 

 bles G. {Hercoceras?) jjaucinodus, Hall, from the Upper Helder- 

 berg group of New York (see Illust. Dev. Foss. , PL 55, Figs. 1 

 and 2), but is less distinctly triangular in a transverse section, 

 that one being widest near the outer portion of the volution, 

 with a nearly regular sloping surface on the side of the whorl to 

 its junction with the preceding one, while this species is rounded. 

 The form of the nodes is also dilfe]"ent — those being situated near 

 the dorsal margin. The triangular form of these nodes is pecu- 

 liar in having the two short sides of the triangle directed forAvard. 

 It also differs in having a greater number of volutions for a given 

 diameter. 



Formation and Localitji. — In limestone of the Upper Helder- 

 berg group, near Dublin, Ohio. Collected by Mr. Ilyatt^ of the 

 State Univcrsitv, at Columbu.'j, Ohio. 



