Genus Pseudorthoceras Girty 

 Pseudorthoceras knoxense (McChesney) 



1860 Orthoceras knoxensis. McChesney, Desc. New Spec. Foss., p. 69, (Date of 



imprint, 1859.) 



Coal Measures: Knox County, Missouri. 

 1866 Orthoceras cribrosum. Geinitz, Garb, und Dyas in Nebr., p. 4, tab. 1, Fig. 5. 



Dyas; Nebraska City, Nebraska. 

 (Most or all of the citations, given under Orthoceras rushense McChesney, possibly 



including McChesney's form.) 



Common in the marine limestones of the Pottsville formation, 

 but not found below the Lowellville member. Although small, 

 representatives vary considerably in size; the form is gradually taper- 

 ing and the siphuncle is central or almost central in position. The 

 septa are moderately convex with about three equaling the diameter 

 of the shell at any point. Variations occur in the latter condition, 

 but the extent of variation cannot be determined as the shells are 

 invariably found in a crushed condition. The peculiar, pitted surface 

 on the Nebraska forms, described by Professor Geinitz as 0. cribrosum, 

 is not apparent on the Ohio specimens, but this difference is in no way 

 significant as the pitted character was probably produced by minute 

 parasites and therefore is not of specific importance. l 



Horizon and locality. Lowellville member: Poverty Run, Mus- 

 kingum County (Locality 19) c; near Sym.mes Ford, Muskingum 

 County (Locality 21), c. Boggs member: near Hopewell P.O. and 

 Rock Cut, Muskingum County (Localities 26 and 28), c. 



Genus Coloceras Hyatt 

 Coloceras ? sp. 



Represented by a small, imperfect specimen from the Sharon 

 ore, the generic relationship of which is very doubtful. 



Horizon and locality. Sharon ore: Lick Run, Scioto County 

 (Locality 2), r. 



Genus Temnocheilus McCoy 

 Temnocheilus forbesianus (McChesney) 



I860 Nautilus forbesianus. McChesney, Desc. New Pal. Foss., p. 63. 



Coal Measures: Mercer County, Illinois. 

 1865 Nautilus forbesianus. McChesney, New Spec. Foss., PI. 3, Figs. 4 a-b. 



Represented in the collections studied by several fragments 

 of the outer volution which preserve fairly well the characters of the 

 outer surface. The form is found more commonly in the horizons 

 above the Boggs. 



Horizon and locality. Boggs member: near Hopewell P.O., 

 Muskingum County (Locality 26), r. 



iGeinitz, H. B., Die Garb, und Dyas in Nebr., p. 4, 1866. 



87 



