40 NEW YORK STATE MUSEUM 



would seem to be supiKji-ted by ihe tiiuiiiij,^ of a specimen of 

 S. b i 1 i lie a I u ni in (lie Rysedorph hill conglomerate by 

 Dr Emmons. There are, however, some facts which combat 

 such a view. These are the observations of Clarke; that the 

 alternation of the striae is more distinct toward the apical 

 region and by rapid intercalation becomes less pronounced 

 toward the aperture; farther, that a shell of S. bilineatum, 

 with a diameter of 7 mm, had only 12 lines of the first order, 

 while the shells under consideration, with a diameter of only 

 3 mm, have already about 20 striae; that no trace of the 

 fine transverse lines, appearing on all stages of 8. bili- 

 neatum, has been observed thus far; and finally that the 

 small shells of Rysedorph hill taper exceedingly slow, while those 

 of S. bilineatum taper quite fast. A fragment J inch long^ 

 shows no meaisurable increase in diameter. O r t h o c e r a s 

 a n e 11 u s Conrad differs in just these features from O. b i 1 i- 

 n e a t u m and it suggests itself that these shells, if not a new 

 ej>ecies, are very likely to be the apical portion of O. a n e 11 u s, 

 hitherto not observed, and also that O. a n e 1 1 u s is a typical 

 Spyroceras. 



S p y r o c e r a s bilineatum has been found to range in 

 the east (Canada) from the Black river into the Trenton beds, in 

 the west to begin in the Stones river beds, and S p y r o c e r a s 

 an e 1 1 u s begins in the Black river beds and extends into the 

 Trer+on. (Uroup 7) 



(Cyrtoceras) subannulatum d'Orbigny •s/>. Trodr. de pal. 1850. 1:1 

 C y r 1 u c-e r a s a n n u 1 a t u m Hall. Pal. N. Y. 1847. 1:104 

 A fragmentary specimen characterized as belonging to C y r t o- 

 ceras annulatum by its strongly arcuate annulations, fine 

 traii/sverse lines and central tubular siphuncle, was found in a 

 pel;ble of greenish gray compact limestone. This species was 

 obtained by Hail from the loWer and upper Trenton beds of 

 New York. (Group 7) 



