190 PAL^ONTOLOGV OF NEW-YORK. 



248. 3. CYRTOLITES FILOSUM. 



Pl. XLI. Figs, 3 a,b 

 Cyrtoceras [Cyrtolites 7 '] filosum, Conrad in MS. Emmons, Geol. Report, 1S42, pag. 372, fig. 4. 



Shell forming a nearly straight, gradually tapering, rounded tube in its upper part, 

 curving towards the extremity, and making little more than half a volution ; surface 

 marked by fine transverse lamellose striae, which bend downwards in an arch on the back 

 of the shell ; section circular. 



This species has been given by Dr. Emmons as a Cyrtoceras, but inadvertently, as he 

 considers it destitute of septa. The specimen figured is the only one known, and it is 

 imperfect towards the aperture. The shell is removed and broken in several places, but 

 reveals no evidence of septa, though the surface markings indicate that it is a cephalopod. 

 I am, therefore, still uncertain as to the true place of this species. 



Fig. 3 a. Lateral view of the specimen imbedded in stone, the apex being concealed. 

 Fig. 3 b. View of the dorsal side of a small portion of the shell, showing the arched strias. 



Position and locality. This species has been seen only in the higher crystalline part of 

 the rock at Watertown, Jefferson county. (State Collection.) 



• 



I have seen fragments of one or two other species of analogous form, where there was 

 no evidence of septa, but have hesitated to arrange them in this association, hoping that 

 that some fortunate discovery would reveal their true character. I am the more doubtful in 

 this matter regarding forms like the Cyrtoceras, since I have learned that the tubes of 

 the true Orthoceras do exist without any evidence of a septate character, while other 

 specimens, precisely similar in every other respect, are provided with septa. The absence 

 of septa, in such cases, does not always appear due to accidental destruction, but to their 

 non-development ; and perhaps the same may be true in regard to those forms like 

 Cyrtoceras. 



