CEPHALOPODA. 271 



Orthoceras profundum. 



PLATE XXXVII, FIGS. 7-9. 



Orihoetrai pro/unc Utm, Hu.l. Descriptions of New Species of Fossils, etc , p. 48. 1861. 



" " 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 striae, which are visible only 

 under a strong lens. These longitudinal ridges and the interspaces are 

 crossed by regular, sharp, transverse, crenulating striae, 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 striae. 



This species, in its surface-markings, resembles 0. Creon, from the Schoharie 

 grit ; O. (Edipus and 0. JEgea, 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. 

 QZdipu.s it is distinguished by the absence of smaller intermediate ridges and 

 annulations, and by its much coarser concentric striae. It has not the annula- 

 tions and low undulations of the tube, as in O. Mgea. 



Formation and localities. In the Upper Helderberg limestone at Williamsville, 

 and Black Rock, Erie county, N. Y. 



