282 PALEONTOLOGY OF OHIO. 



species of. Strophomena. Indeed, it is now well known that this charac- 

 ter of the elevation of the beak, and the greater or less development of 

 the area can not be, within a considerable range of limits, even relied 

 upon as a specific distinction 



Locality and position : The specimens from which our figures and description were 

 prepared were found in the Waverlj^ group of the Lower Carboniferous, in Medina 

 count}', Ohio. It also occurs at numerovis other localities in this State at the same 

 horizon, and I suspect that some of the Devonian forms that have been described 

 under other names farther eastward may not be specifically distinct. According to 

 some very high authorities, R. crenistria occurs both in the Carboniferous and Devon- 

 ian rocks of Europe. It is certainly a very widely distributed Carboniferous species, 

 its geographical range there being almost coextensive with the rocks of that age. 



Genus PRODUCTUS, Sowerbj, 1814. 



(Min. Conch., I., 153.) 



Productus (undetermined sp.). 



Plate 10, figs. 4a, b, c, d. 



At the time the figures of this and the following form were drawn, it 

 was my intention to make a thorough study of the Producti and other 

 Brachiopoda of the Waverly group, and to prejmre full illustrations and 

 descriptions of them all. A failure of health, however, rendered it im- 

 possible to carry out this design. 



The species here under consideration attains a medium size, has a very 

 gibbous, strongly arcuate, and produced ventral valve, faintly sinuous 

 along the middle, with short ears extending little beyond the lateral 

 margins, and a concave, transversely semi-oval dorsal valve. Its hinge 

 equals about the greatest breadth of the valves, and its surface is armed 

 with small, apparently short spines, that are moderately scattering, and 

 regularly arranged in quincunx, on little tubercles that become more or 

 less elongated on the ventral valve, where they sometimes even assume 

 the character of irregular costaj. These are crossed by very fine, regular, 

 crowded, concentric striae, and small, generally obscure, concentric 

 wrinkles, that are most regular and best defined over the visceral region 

 of both valves. The costae are very variable, being sometimes rather 

 distinct, and in other cases quite obscure, or almost entirely obsolete, so 

 that the surface seems nearly smooth between the little tubercles. 



It is probably an undescribed species, but the difficulty of distinguish- 

 ing species in this group is so great, without a good series of specimens 

 and authentic examples of the closely allied s^jecies for comjjarison, that 

 I have concluded not to attempt to decide the question in regard to its 



