314 PALEONTOLOGY OF NEW YORK. 



which, upon the outer chamber, become elevated into strong, prominent 

 annulations. Surface marked by fine, irregular lines of growth and longitu- 

 dinal stria), of which there are three in the space of one mm. 



A fragment with a length of forty mm. shows five distinct annulations at 

 the larger extremity, and about twenty air-chambers throughout the length 

 Fifteen air-chambers occupy the smaller half of the fragment, which is with- 

 out annulations. A fragment of a larger individual shows ten air-chambers 

 in the length of fifteen mm., and three annulations in the same space along 

 the larger adjacent, non-septate portion of the tube. 



This species is remarkable for the frequency of the air-chambers, the very 

 excentric position of the siphuncle, and the strongly annulated chamber of 

 habitation, with an absence of this ornamentation over the greater part of the 

 septate portion. These characters distinguish it from all the other species 

 here described. 



Formation and locality. In sandstones belonging to the Upper Chemung, at 

 Warren, Pa. 



Orthoceras pertextum, n. sp. 



PLATE XC, FIGS. 16, 17. 



Shell straight, gradually enlarging. The other characters, except those of 

 the ornamentation of the tube and the surface-markings, have not been 

 observed, owing to its fragmentary mode of occurrence. 



Tube ornamented by regular, prominent annulations with concave inter- 

 spaces, about five in the length of twenty mm. Surface crenulated by fine 

 transverse stria;, which are crossed by equally fine, regular, longitudinal striae. 



A fragment with twelve annulations has a length of sixty-five mm., and a 

 diameter in its compressed condition of about twenty-five mm. 



This species is distinguished by its surface-markings, from any of the other 

 annulated forms, described in this volume. 



Formation and locality. From shales of the Chemung group, near Ithaca, N. Y. 



