74 FIFTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



ORTHOCERAS FOLIATUM ( n.s.). 7 1/ ■ 

 Shell elongate, very gradually tapering : septa comparatively 



distant ; sipliuncle unknown. 

 Surface marked by fine concentric striae, and, at intervals correspon- 

 ding with the septa, the shell extends in lamelliform expansions 

 at nearly right angles to the axis, or inclined a little towards the 

 aperture : these lamelliform expansions are gently curved down- 

 wards on the back of the shell, and abruptly bent on the dorsal 

 line, leaving a sinuosity in the margin of the aperture. 

 A specimen, of which the shell only is preserved in the stone, 

 measures more than seven and a half inches ; and in this space are 

 twenty-two projecting ridges, some of which extend more than a 

 quarter of an inch beyond the body of the shell : in the middle 

 there are about three of these ridges, or a little less, in the space 

 of an inch; but at the larger extremity, or towards the aperture, 

 they are more crowded, giving five in the space of an inch. In an- 

 other specimen, three spaces occupy an inch and a quarter; and in 

 a cast of the interior, they present about the same proportions. 



This species is not uncommon in fragments or impressions of the exterior ; 

 and the similarity of these impressions to those of Cyrtoceras eugenium 

 suggests a relation between the two, but in this one the strong annulations 

 continue almost to the aperture, while in that species they do not. If this 

 be a Cyrtoceras, it bears nevertheless an undeviating straight line for at 

 least eight inches. 



Geological formation and locality. In the Schoharie grit : Helderberg 

 mountains, and Schoharie. 



d c 



ORTHOCEEAS BACULUM ( n. s.). ^ L 



Shell cylindrical, scarcely tapering : outer chamber very long; 



septa somewhat deeply concave, distant more than one-third the 



diameter of the shell. Sipliuncle excentric. Surface unknown. 



This species is remarkable for its slender cylindrical form. A 



specimen five ajid a half inches long, and preserving more than 



three inches of the outer chamber, is scarcely appreciably diminished 



towards the apex, the greatest actual diameter being in the middle 



of the length. Another fragment of nearly four inches in length, 



of which an inch and a half pertains to the outer chamber, shows 



scarcely a diminution in the diameter. The first of these specimens 



has a diameter of five-eighths of an inch, and the second, of half 



[ September, 



