i68 Ciiiciiniaii Society of Xatural flistory. 



Trematoceras ohioense, n. sp. 



Plate 6, Fig. 4, lateral vie'v, natjiral size ; Fig. 5, dorsal view, 

 looking forwa rd. 



Shell medium or below medium size, discoidal, rather 

 rapidly enlarging. Umbilicus broad, showing all the inner 

 whorls and perforated in the middle. Volutions gradually in- 

 creasing in size, coming in contact, without embracing, 

 broader transversely than dorso-ventrally. The sides of the 

 volutions are narrowly rounded, the dorsum bears a wide de- 

 pre.s.sed convex keel in the central part, with a depressed 

 sulcus or concave furrow on each side, bounded laterally by 

 an obtuse angle. Surface ornamented with fine longitudinal 

 lines. 



Septa moderately concave and distant nearly one-fourth the 

 transverse diameter ; they arch backward in crossing the 

 dorso-lateral furrows and slightly forward in ascending the 

 median ridge, which they cro.ss transversely without extending 

 as far forward as they do on the sides of the volution. Body 

 chamber long, continuing to gradually enlarge and bearing 

 the dorsal keel and furrows. Aperture and siphuncle un- 

 known. 



This species most resembles 7". trisiileatus, from which it is 

 distinguished by being proportionally wider, transversely, 

 more narrowly rounded on the sides of the volutions, shallower 

 dorso-lateral furrows, and convex instead of furrowed median 

 keel ; neither do the septa extend as far forward in crossing 

 the median dorsal ridge. 



Found near Sciotoville and near the top of the hill, in rocks 

 usually classed with the Waverly (iroup, but they are above 

 the Waverly sandstone proper, and belong to the upper part 

 of the Subcarboniferous system. The specimens examined 

 belong to the collection of Charles Faber. 



