Pah'outolooy of I be (iiiciniia/i Croup. 157 



Leptotrraptiis {Graptolit litis) sub-tcnitis, Hall (s])). This is a 

 Norman's Kill, New York, form, and I should doubt very 

 strongly its presence in the Cincinnati group. There can be 

 no question whatever as to the distinctness of Portlock's and 

 Hall's species, and I strongly suspect the Cincinnati form is 

 referable to neither." 



Upon this authority, therefore, what has been called at Cin- 

 cinnati G. oracilis is referred to Jhiidroorap/iis graci/liniiivi, 

 (which see ante) ; and (i. sttb-tcniiis is dropped altogether. 



Genus 2. — Diplograptus, McCoy, 1S54. 



Polypary composed of two simple, monoprionidian stipes, 

 united back to back, their dorsal walls uniting to form a 

 median septum, along the center of which runs the solid axis ; 

 cellules alternating with one another on the two sides of the 

 frond, the cell mouths being situated at the end of projecting 

 denticles; base usually furnished with a radicle, and the solid 

 axis probably always prolonged beyond the distal end of the 

 polypary. (Nicholson, Mon. Brit. Grap., 1872, p. 115). 



Rouarks. — McCoj^'s original description of this genus con- 

 sists of the statement that he restricts Graptolithiis to those 

 species having cells only on one side. For those with cells on 

 both sides he proposed Diplograpsiis [now DipIograptiis\. 

 (Brit. Pal. Foss., 1854, p. 3). 



Of the two species commonly referred here, one {spinulosiis) 

 has been placed in the genus iilossograptiis. The other 

 ( WJiitfieldi) remains with the genus. Both are, however, here 

 retained in Dip/oorapiiis, as I can not see the justice of sep- 

 arating the two species. Glossograpius was defined as fol- 

 lows : " Column free ; thin membranaceous, ligulate, extremi- 

 ties rounded, axis distinct." (Emmons, Amer. Geology, pt. 

 2, 1856, p. 108). 



I. — D. spiNULOSUvS, Hall, 1859. 



Stipe simple, flat; sides sub-parallel, gradually expanding 

 from the base, which is furnished with several minute setiform 

 radicles; serratures not distinct, the margins sinuous; the 

 principal parts extended into slender, spiniform processes. 

 These spinules are about one-sixteenth of an inch apart. 

 (Paleont. of New York, vol. 3, 1859, p. 517.) 



Locality. — Cincinnati, O. 



