CEPHALOPODA. 
27 L 
Orthoceras profundum. 
PLATE XXXVII, FIGS. 7-9. 
Orthoceras profundum, Hall. Descriptions of New Species of Fossils, etc , p. 43. 1S61. 
“ “ “ Fifteenth Rep, N. Y. State Cab. Nat. Hist., p. 76, pi. 7, fig-. 8. 1862. 
“ “ “ Illustrations of Devonian Fossils: Cephalopoda. Explanation of plate 37, 
figs. 3-6. 1876. 
Shell straight, regularly and gradually enlarging from the apex to the aperture. 
Transverse section circular. Apical angle 4°. Initial extremity unknown. 
Chamber of habitation well developed. Its full extent has not been 
observed. Air-chambers, septa and siphuncle unknown. 
The test, as preserved on the chamber of habitation, has a thickness of 
nearly .5 mm. Surface marked longitudinally by sharp ridges, distant 
from each other two to four mm. where the tube has a diameter of about 
thirty-five mm., with very fine intermediate strife, which are visible only 
under a strong lens. These longitudinal ridges and the interspaces are 
crossed by regular, sharp, transverse, crenulating strife, of which there are 
seven in the space of five mm. There is a gentle sinus in the transverse 
ornamentation over the ventral side. 
The internal mould retains the imprint of the strong longitudinal ridges, 
and the transverse strife. 
This species, in its surface-markings, resembles 0. Creon, from the Schoharie 
grit; 0. (Edvpus and 0. PEgea, from the Hamilton group; the four species 
constituting a natural group with the cones fluted. It differs from 0. Creon 
in its more gradual enlargement and distant longitudinal ridges. And from 0. 
(Edipus it is distinguished by the absence of smaller intermediate ridges and 
annulations, and by its much coarser concentric strife. It has not the annula- 
tions and low undulations of the tube, as in 0. PEgea. 
Formation and localities. In the Upper Helderberg limestone at Williamsville, 
and Black Bock, Erie county, N. Y. 
