CejjJiahpoda of the Cincinnati Group. 125 



dimiuisliing in size, as the distance between the septa becomes less and 

 less. Greatest diameter of the siph uncle about or a little more than 

 one fourth the diameter of the shell. Outer chamber more than one 

 fourth the length of the shell, measuring to the end of the siphuncle. 

 Outer surfoce of the shells in good specimens smooth, and not showing 

 the septa within. 



Polished specimens show septa commencing to form in the body 

 chamber, in advance of the siphuncle ; those near the siphuncle 

 approaching, while those more distant only commencing to leave the 

 outer shell. 



I found this species near Versailles, Ind., about 300 feet below the 

 Upper Silurian rocks, associated with Anoclontopsis MUeri, Anmaalo- 

 clojita gigante't, Modinhpsis Versailksensis, CyHo/ites ornatus, showing the 

 outer shell and surface markings, and other fossils better preserved 

 than I have found them elsewhere. The specific name is given in 

 honor of our paleontological friend, Paul Mohr, Sr., Esq. 



Orthoceras Dyeri — (S. A. Miller). 



Fig. n.— Orthoceras Dyeri. Longitudinal section showing siphuncle. 



Shell rather rapidly tapering; outer surface unknown. Septa 

 highly arched and distant about one fifth the diameter of the shell. 

 Siphuncle large, subcentral, varying in position, and presenting the 

 appearance of a string of flattened oblate spheroidal beads, having the 

 same inclination as the septa, between which they are placed. Great- 

 est diameter of the siphuncle about one-third the diameter of the 

 shell, and therefore more than one and a half times the distan«-e 

 between the septa. Chamber of habitation unknown. 



Found on the hills back of Cincinnati, but the range is unknown. 



The specimen figured is from the collection of C. 1>. Dyer, Ks:|., 

 in whose honor I have given the specific name. The nphuncleis rep- 

 resented in the figure a little narrower than it should be. 



