148 PALEONTOLOGY OF ILLINOIS. 



CLASS CEPHALOPODA. 



GENUS NAUTILUS. Breynius. 

 NAUTILUS MONTGOMERYENSIS. Worthen. 



PL XXVI, Fig. 2 and XXVII, fig. 1. 



Nautilus montg ornery ensis, Worthen, March, 1884. Bulletin No. 2, of the Illinois State 

 Museum of Natural History, page 4. 



Shell of medium size, sub-globose, volutions two or more, 

 rapidly expanding ; outer septum regularly rounded in front and 

 on the sides, wider than long, with a wide and deep sinus in 

 the middle of its dorsal border for the reception of the broad 

 tongue-like projection of the next septum. The succeeding septa 

 are much narrower, and more broadly curved on their dorsal 

 sides, with a long and broad tongue-like projection in the 

 middle that fills the sinus of the preceding septum. Position of 

 the siphuncle unknown. The specimen is a cast in clay iron- 

 stone and shows no surface ornamentation. 



Aperture reniform in shape, and 3 3 / 34 inches in breadth by 

 1% inches in height. Length of the shell from front to back 3% 

 inches. 



Position and locality: Upper Coal Measures, Montgomery 

 county, 111. 



Collector unknown. 



No. 2544 of the Illinois State Museum. 



GENUS OETHOCERAS. Breynius. 

 ORTHOCERAS ILLINOIENSE. Worthen. 



PL XXVI, Figs. l,la, Ib. 

 Orthoceras illinoiense, Worthen. 1883. Qeol. Surv. of Illinois, Vol. VII, page 323. 



Shell of medium size, gradually enlarging from the apex; sec- 

 tion slightly ovate, siphuncle rather large, and placed near the 



