502 NEW YORK STATE MUSEUM 



with a shallow wide hyponomic sinus. Cameras very shallow, in- 

 creasing to more than double width from the earlier stages to the 

 ephebic stage (lo in lo mm in nepionic stage and 4 in the same 

 space in the ephebic stage) ; sutures provided with a narrow, low 

 dorsal and a faint broad ventral saddle, in young specimens straight. 

 Septa shallow, their concavity approximately ec^ual to the depth of 

 the cameras. 



Siphuncle large, 5 mm wide in 

 ^-— -' — -~ — the septal perforations, slightly 



/ "V contracting between the septa, pro- 



\, piodorsan in position ; without any 



\ organic deposits. 



■ { Position and locality. In the 



J Fort Cassin beds at Fort Cassin. 



Observations. This interesting 



form was referred by its author to 



;--^ . -J' Gomphoceras but the very slight 



"--=.^;^::;::^^^U y development of the lateral contrac- 



^'^Z^ '' _ . ■ l_:.^ tion of the apertural margin, dis- 



^~~" "^ tinctly shown in our material, 



TT- . r .1 Of i^».,e.c= proves it to be of a more primitive 



Fig. t,6Cyclostomicerascas- r f 



sinense whitf. (sp) Long^itudinai character than Gomphoceras, and 



section of fragment snowing the t' ' 



living chamber, siphuncle and depth ^j-^g Phragmoccratidae in general. 



of septa. X }x ^ o ^ 



Hyatt has made it a genotype and 

 referred the new genus to the Oncoceratidae ; describing it as 

 consisting of exogastric forms. Since our specimens have the hypo- 

 nomic sinus on the flat or less arched side, this form seems to have 

 relations to or could be conceived to lead to the endogastric genus- 

 Phragmoccras. 



The position of the hyponomic sinus on the flatter side indicates 

 that the animal carried the conch very much in the position given 

 to it in the lateral view [pi. 37, fig. 3]. 



Cyclostomiceras minimum Whitfield (sp.) 



Plate 3S, figure 5, 6 



Gomphoceras minimum Whitfield. Amer. Mus. Nat. Hist. BuL 

 1886, V. I, no. 8, p. 321, pi. 27, fig. 3-5. 



Observations made on specimens in the collection of Burlington 



University verify the statement contained in the original description, 



that this form had an open aperture, the margins of which were not 



contracted. It, therefore, can not be referred to Gomphoceras but 



