620 Ruth R. MooTc—A New Cephalopod. 



about 25 mm (varying according to state of compression) ; num- 

 ber of whorls 4, the outer one incomplete ; increase in diameter 

 of whorls very gradual ; diameter of inner whorl about 10 mm ; 

 septa simple, very slightly curved, about 4 ram apart on outer 

 whorl and 3 mm apart on inner side of inner whorl ; annulations 

 on outer whorl about 2"5 mm apart ; siphuncle ventral. 



Owing to the crushed condition and poor preservation of 

 the shell the extent of the elevation of the spire is unknown. 

 From the irregular warped surface of the specimen it seems 

 reasonable to suppose that the spire was very broad and low. 

 The exact nature of the umbilicus is indeterminate ; presum- 

 ably it was broad, shallow, and not angular. The precise 

 character of the siphuncle is also unknown. There is only 

 one place on the shell where the siphuncle appears ; here it is 

 only very poorly preserved. Its ventral position, however, 

 can be determined. 



Trochoceras grovaniense seems most nearly related to T. 

 priscam Barrande, Etage 2 of Bohemia. It differs from the 

 latter in its greater size, more gradual increase in the size of 

 the whorls, an d n having the septa straighter and slightly 

 farther apart. 



Paleontological Laboratory, Columbia University. 



