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ART. XX. — Description of a Fossil Saurian of the New Red Sandstone Formation 

 of Pennsylvania ; rvith some account of that Formation. 



By Isaac Lea, 



The existence of " fossil footmarks " was received with great doubt by geologists, 

 when first announced, and it required numerous observations before such geological 

 evidence was generally accredited. 



It appears that Dr. Duncan first noted these interesting and peculiar relics of 

 ancient life, in 1828, having observed the impressions made by tortoises in the " New 

 Red Sandstone " of Dumfriesshire in Scotland. A few years after this, among other 

 discoveries, was that of the tracks of the Cheirotherium {Lahyrinthodon of Owen) in 

 Saxony, where it was found also in the " New Red Sandstone." 



In this country. Dr. Deane and Professor Hitchcock observed fossil footmarks in 

 the " New Red Sandstone " of the Valley of the Connecticut River, the age of which 

 has been recently doubted by Elie de Beaumont and Dr. Jackson, who think it 

 belongs to a lower member of the series. I do not myself incline to that opinion, having 

 no doubt of its being a member of that group of red sandstones which form the masses 

 between the carboniferous strata and the Lias. In 1836 Professor Hitchcock published 

 his account of bird tracks, (Ornithichnites,) in the American Journal of Science, and 

 his statements were received with a good deal of doubt, until, by repeated observations 

 and publications by himself and others, geologists generally became satisfied with 

 the established fact, that while there had not been found a single bone in these rocks, 

 yet the undoubted foot-prints of numerous species of birds and reptiles, gave the 

 fullest and most satisfactory evidence that, at that geological epoch, immensely 

 remote, the plastic shores of these waters received the impression of numerous air 

 breathing animals. Prof. Forbes has recently observed that "the symmetry with 

 which the prints succeeded each other on the surface of the sandstone, &c., furnished 

 an agreement, geometrical, no doubt." 



Two years subsequently various foot-marks were found in the New Red Sandstone 

 near Liverpool, and, subsequently again, they were found in various parts of 

 England, and on the continent, in the same formation, as well as in more recent 

 strata. 



In the Valley of the Connecticut, Professor Hitchcock informs us, that sixteen 

 quarries are known to produce foot-marks, and Mr. Redfield has observed them at 

 Pompton, in New Jersey ; and, more recently, they have been found near Princeton, 

 New Jersey, by Mr. Jones, an industrious young naturalist of the College there. In 



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