314 
PALAEONTOLOGY OF NEW YORE. 
which, upon the outer chamber, become elevated into strong, prominent 
annotations. Surface marked by fine, irregular lines of growth and longitu¬ 
dinal striae, 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 striae, 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. 
