On Some Peculiar Impressions in Sandstone. 203 



^ HIPPODOPHYCUS nov. gen. 

 [HipPODOPHYCUs n. g., in abstract of this paper distributed in August, 1869.] 



Marine plants, having swelling roots, whicli are laterally expanded in 

 the form of a snbcircular disc, with one edge truncate, and having 

 the upper and lower surfaces deeply impressed ; leaving a thickened, 

 rounded rim to form the margin of the disc, except on the tnmcate 



K portion, where the substance becomes thin and attenuated, and the 



. central depression opens out to the margin. 



The bodies for which the above generic name is proposed are 

 known only from their impressions left on the surfaces of the layers 

 of sandstone where they occur. The cavities are of the form of that 

 which a ball of putty or other soft substance would assume, if pressed 

 between the thumb and finger so as to compress the center and one 

 margin, leaving a rounded rim on three sides of the disc so formed, 

 the compressed margin being truncate, and the extremities of the 

 rim being also laterally compressed. The cavities are mostly placed 

 horizontally in the rock ; and, as they occur on the surface of the 

 layer, only one side of the cavity is presented, the other portion hav- 

 ing been removed by the displacement of the upper layer of rock, or 

 perhaps by a shaly or softer parting layer. The junction of the stem 

 and rootlets with the disc has, most likely, been at the thin edge of 

 the disc, as there is a kind of cicatrix observed on some of the 

 impressions at this point. The surface of the impression is rough- 

 ened and sometimes corrugated, as would be natural to the surface of 

 a root ; but usually all surface characters have been obliterated by 

 the action of fire in burning off the timber from the field in which 

 they occur, and also somewhat by subsequent weathering. 



The impressions occur on a thick layer of sandstone conglomerate, 

 found in many places in Cattaraugus county, New York. There are 

 associated in the same beds two species of Ptekinea, one Aviculo- 

 PECTEN, one Edmondia, a Sanguinolites, and one or two other unde- 

 termined lamellibranchiate shells ; one Spirifer, apparently Sp. 

 Verneuili of the New York Chemung rocks, and an undetermined 

 Rhynchonella {R. Stejphcmii f). The impressions are found at Sala- 

 manca, Randolph and South Yalley, Cattaraugus county, New York. 

 Some of those of the latter locality are smaller and of a little difi'er- 

 ent form, and are known by the name of " elk tracks." Both forms 

 are also said to occur in a sandstone of similar character at Quaker 

 Hill, north of Warren village, Warren county, Pennsylvania. 



