190 
PALAEONTOLOGY OF NEW-YORK. 
248. 3. CYRTOLITES FILOSUM. 
Pl. XLI. Figs. 3 a, b 
Cyrtoceras \Cyrtolites ? ] filosum, Conrad in MS. Emmons, Geol. Report, 1842, 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 striae. 
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. 
