FOSSILS OF THE NIAGARA GROUP. 149 



mined from the filling of the chambers and the adhering rock. These 

 differences, being so slight, have not been deemed of sufficient importance 

 to require a distinct specific designation. 



Formation and locality : In the limestones of the Niagara group, at Cedarville, Greene 

 county, Ohio. Collected by Rev. H. Hertzer. 



Orthoceras strix (n. sp.). 



Plate 9, fig. 3. 



Shell rather large, somewhat rapidly expanding from below upward, 

 increasing from a diameter of one and a quarter inches to exactly twice 

 that diameter in a length of seven inches ; transverse section broadly 

 oval, or sub-circular, the greater flattening of some examples having 

 been caused partly by compression, as is shown by the more nearly cir- 

 cular form of the lower extremity of the specimen figured. Septa strong, 

 moderately concave, and widelj'^ separated, being a little more than half 

 an inch distant from each other in the examples studied, and the distance 

 apparently not increasing with the increase of the shell. Siphuncle 

 sub-central, proportionally not very large. Surface of the cast marked 

 by strong, longitudinal flutings, which measure nearly or quite half an 

 inch from crest to crest at the upper end of the specimen figured, and a 

 little more than a fourth of an inch at the lower extremity of the frag- 

 ment; interspaces regularly concave. The surface of the shell has ap- 

 parently been longitudinally striated in the flutings, as is shown by a 

 fragment of shell adhering to the cast in the depression of one of the 

 flutings, but no evidence of transverse strife, like that on some species 

 of this group, has been seen. 



This species bears considerable resemblance to 0. columnare, Hall, but 

 besides having the flutings of much larger size in comparison, the shell 

 tapers much more rapidly than any of the forms referred to that species. 

 Compared with 0. cadmus, Bill, Sil. Foss. Anticosti, p. 83, it differs very 

 materially in the more rapid increase in size, and in its oval section. 



Formation and locality : In limestones of the Niagara group, at Yellow Springs, Ohio. 

 Collected by Prof. Edward Orton. 



Genus CYRTOOERAS, Goldf. 

 Crytoceras myrice (n. sp.). 



Plate 8, fig. 9. 

 Shell rather below the medium size, very moderately expanding from 

 below upwards, but a little more rapidly below than above the middle of 

 the length ; a slight constriction just below the margin of the aperture 



