308 PALEONTOLOGY OF NEW-YORK. 



369. 4. CfYRTOLITES ORNATUS. 

 Pu LXXXIV. Figs. 1 a, ft, e, d, e,f, g. 



Cyrtolitei omatut. Conhad, Ann. Geol. Rep. New-York, 1838, p. IIS; 1839, p. 63; 1841, p. 37. 



— — VxNUxrM, Geol. Report, 1842, pag. 65, Bg. 2. 



— — EnMONs, Geol. Report, pag. 402, fig. 2. 



Convolute ; spire equally depressed on either side ; volutions two or three ( rarely more 

 than two visible ) , rapidly enlarging towards the aperture ; shell sharply and strongly 

 carinated upon the back, and obtusely angulated upon the sides ; ventral side obtusely 

 angulated, with a narrow deep groove on the summit, for the reception of the dorsal 

 carina ; aperture but slightly expanded, quadrangular ; section quadrangular ; dorsal slopes 

 marked by strong obliquely transverse ridges, which extend to the angle on the side of 

 the volution ; entire surface marked by fine transverse striae, the spaces between which are 

 crossed by finer curving ones, giving the surface a cancellated or pitted appearance. 



This fossil usually occurs in the form of casts of the interior, which preserve the form 

 of the shell, the dorsal carina, and the transverse ridges, but not the finer sculpture of the 

 surface. In the perfect shell the volutions are contiguous, there being a narrow groove on 

 the ventral line for the admission of the dorsal carina. In casts of the shell, the volutions 

 are often not contiguous, owing chiefly to the dorsal carina being broken ofl^; for when the 

 cast of this part is preserved, it usually reaches to the ventral side of the contiguous 

 volution. This fossil is one of the most remarkable and characteristic of the group, and 

 80 peculiar in its form and markings as to render it easily identified. 



This species is the type of the Genus Cyrtolites, proposed by Mr. Conrad, 



Fig. 1 *. Lateral view of a cast of this species. 



Fig. 1 b. Profile of the same, looking into the aperture. 



Fig. 1 c. Another specimen (a cast), where the volutions are contiguous. 



Fig. W. A specimen preserving the shell, from which the finer striae are removed. This fossil, though 

 still preserving the shell, has the exterior often exfoliated, destroying the beautifully sculp- 

 tured surface. 



Fig. W. A portion of the surface of the shell, showing the sculpture. 



Fig. 1 /. A portion of the same magnified. 



Fig. 1 g. A transverse section of the shell. 



Position and locality. This species is unknown in the Trenton limestone, or Utica slate, 

 but is abundant in the central and higher part of the Hudson-river group. It is found at 

 Turin, Boonville, Rome, Pulaski, Washingtonville, Loraine, Rodman, and numerous 

 other localities, in New-York. It occurs in the same position in Canada, and in several 

 western localities. (Stau Collection.) 



