Description of Some Cincinnati Fossils. 



145 



posed to include such species as Orthodesma byrnesi, Ortho- 

 desma mickelboroug hi and Sedgzcickia {?) lunulata. Whitfield, 

 when he described Orthodesma mickelboroughi and Scdg- 

 wickia {?) lunulata never, for a moment, suspicioned that they 

 could be congeneric. Sedgwickia (?) lunulata is nearly 

 equilateral, and has somewhat the form of two dorsally- 

 rounded Bellerophons, with their ventral sides and mouths 

 pressed together. The authors have good specimens of the 

 species, and can not imagine how any one, with any knowl- 

 edge whatever of shells, could think of classing Sedgwickia (f) 

 lunulata with Orthodesma mickelboroughi and Orthodesma 

 byrnesi. As we have shown above, the species under consid- 

 eration is most clearly an Orthodesma, and for the same 

 reasons O. mickelboroughi is a true Orthodesma, and we would 

 as soon think of proposing a new generic name for the type 

 of the genus Orthodesma as for O. mickelboroughi . Not a 

 shadow of a reason is suggested why Orthodesma byrnesi 

 should be removed from Orthodesma, and we have not discov- 

 ered any reason for so doing. From the present state of 

 learning in regard to these fossils, it would seem that Rhy- 

 timya may be relegated to synonymy. 



The species above described is not very uncommon in the 

 upper part of the Hudson River Group, in Warren County. 

 Ohio, and the specimens illustrated are in the collections 

 belonging to the authors. 



Orthodesma scaphula n. sp. 



Plate 8, Fig. 10, view of the right valve; Fig- 11, cardinal view 

 of the same specimen. 



This is a small species, much below the average size, and 

 most nearly related to Orthodesma cymbula above described. 

 Shell elongate, a little more than twice as long as wide, and 

 about one half wider than thick. Subelliptical in longitu- 

 dinal outline, though most cuneate posteriorly. Beaks small, 

 obtuse, situated about one-sixth or one-seventh of the entire 

 length of the shell from the anterior end and approximate. 

 Cardinal line straight posterior to the beaks for about one- 



