May, 1917] Silurian Fossils from Ohio 257 



The brachial valve here described was found in slabs that 

 had dropped from the Eridorthis horizon at Ivor, Kentucky. 

 At this locality the Fulton clay, characterized by the presence 

 of Triarthrus becki, Green, occurs 70 feet above the level of the 

 railroad track. A single specimen of Eridorthis once was found 

 in the layer of limestone immediately beneath the Fulton clay, 

 but the species is much more common in some of the overlying 

 horizons, although, owing to the steepness of the quarry-face, 

 the exact location of this horizon is difficult to determine here. 



At the quarry west of Point Pleasant, Ohio, the Fulton clay, 

 containing Triarthrus becki, is about 55 feet above the level of 

 the pike. The immediately underlying layer of limestone is 

 strongly ripple marked, and a single specimen of Eridorthis was 

 found imbedded in its upper surface. Loose limestone slabs, 

 containing a greater number of specimens of Eridorthis, were 

 found at 14, 20, and 27 feet above the base of the Fulton layer. 

 Evidently Eridorthis must be abundant somewhere above these 

 horizons. 



At the quarry in the northeastern part of New Richmond, 

 Ohio, the Fulton clay, containing Triarthrus becki, has a thick- 

 ness of at least five feet. A specimen of Eridorthis was found at 

 the top of the immediately underlying layer of coarse grained 

 limestone. Eridorthis, associated with a Leptcena, provisionally 

 identified as LeptcBua gibbosa, James, is comparatively abundant 

 in a thin layer of limestone occurring within one foot above the 

 base of the Fulton clay. Eridorthis occurs in situ also in a four 

 inch layer of conglomeratic limestone, located about 29 feet 

 above the base of the Fulton clay. This may have been the 

 horizon which furnished the loose slabs, containing Eridorthis, 

 in the quarry west of Point Pleasant, Ohio, and this also may 

 have been the approximate horizon for the specimen of 

 Schuchertella higginsportensis, obtained at Ivor, Kentucky. 



Schuchertella has not been identified hitherto from strata 

 below the Silurian. It may be that when the material now 

 congregated under Schuchertella is studied more closely that 

 species here described as Schuchertella may be separated from 

 that genus, but at present this reference to Schuchertella appears 

 at least more logical than its former reference to Strophomena. 



The exterior of a brachial valve, figured here (Fig. 2B) as 

 belonging to Schuchertella higginsportensis, is characterized by 



