496 PALAEONTOLOGY OF ILLINOIS. 



It is barely possible that this may be a veutricose, fusiform ]\[urcM- 

 sonia, as we only know it from rough casts, apparently of the exterior. 

 As it shows no traces, however, of any revolving baud, or lines, and has 

 much the general physiognomy of Subulites, we have concluded to refer 

 it provisionally to that group. Its most marked characters are the large 

 size, and the veutricose form of its body volution, in which it reminds 

 one of some of the Carboniferous species of Macrocheilus. It differs 

 from these, however, in the produced and subcaualiculate peculiarity of 

 the lower part of its body whorl. 



Position and locality: Galena beds of the Lower Silurian; Carroll 

 county, Illinois. 



CEPHALOPODA. 



Genus OYETOCERAS, Goldf. 



Cyetoceeas Caeeollensis, Worthen. 

 PI. -y-yrrr, ri g . 3. 



Shell of medium size, moderately curved and laterally compressed. 

 Section ovate, the greatest diameter being near the middle of the cham- 

 ber of habitation, which is strongly constricted above the middle, and 

 about an inch in depth. Septa about eight to an inch on the dorsal 

 side. Dorso- ventral diameter of the last chamber 7 lines, lateral diame- 

 ter of same o lines. Siphuncle of moderate size, dorsal and nearly in 

 contact with the shell. Surface markiilgs unknown. 



This shell seems to be nearly related to C. macrostomum, of Hall, 

 Palseont. of N. Y., Vol. I, page 194, PI. 42, fig. 1, and also to G. Isodorus, 

 of Billings, Paleozoic Fossils of Canada, Vol. I, page 175, but may be 

 distinguished from both by the characters given above. ' 



Position and locality : Galena division of the Lower Silurian ; Carroll 

 county, Illinois. 



