GEOLOGY. 315 



Iron. The disproportion in the gize of the fore and hind feet is such 

 as we find in some existing terrapins e. g., the Emys geographical 

 At the meeting of the American Association, Albany, Mr. T. S. 

 Hunt, of the Canadian Geological Survey, stated, that during the past 

 summer, similar tracks have been discovered, in large numbers, in dif- 

 ferent beds, and at distances several miles apart. There is a great 

 diversity in their size, but they agree in their general characters. The 

 beds containing them are lying at a very small angle, and are overlaid 

 by undoubted calciferous sandstone, while to this formation succeeds 

 the Trenton limestone with its characteristic fossils. 



ON SOME REPTILIAN FOOT-MARKS OF THE INFRA-CARBONACEOUS RED 



SHALE OF PENNSYLVANIA. 



PROF. H. D. ROGERS exhibited to the geological section of the Amer- 

 ican Association, Albany, specimens of impressions on the infra-carbona- 

 ceous red sandstone of the anthracite region of Pennsylvania, and sub- 

 mitted a description of their forms. These marks are of at least three 

 species. They are all of them five-toed, and in double rows, with an op- 

 posite symmetry, as if made by right and left feet, while they likewise 

 display the alternation of fore foot and hind foot. In other words, they 

 are evidently quadrupedal. One species, the largest discovered, presents 

 a diameter for each foot-print of about two inches, shows the fore and hind 

 feet to be nearly equal in dimensions, displays a length of stride of about 

 nine inches, and a breadth between the right and left treads of nearly four 

 inches, and it shows the hind feet very little in the rear of the forefeet. 

 This disposition of the footsteps, and other features described, were 

 deemed, by Prof. Rogers, to ally the animal which made them rather to 

 the saurian reptiles than to the batracians or chelonians ; but he wished 

 to speak doubtingly of a point so difficult of decision in the present state 

 of our information. Another series of smaller impressions displays also 

 the quadrupedal indications, there being the same alternation of fore 

 and hind, and of right and left feet ; but the intervals between the 

 fore and hind feet are about equi-distant. In this species, the width 

 between the right and left feet is more than half the length of each 

 stride. Associated with these footmarks are all the evidences of a sub- 

 aerial exposure of the surfaces on which they are impressed, as sun 

 cracks, rain-spotting, and the signs of the tricklings of a wet, sandy 

 beach. All these associations confirm the inference, from the form of 

 the foot-prints themselves, that the animals imprinting them belonged 

 to air-breathing, and not to aquatic races. 



Professor Agassiz was disposed to combat the views advanced, that 

 these were the foot-prints of some tribe of reptilian animals, and he 

 ventured to conjecture that they might more probably have been made 

 by articulated animals. He indicated how certain families of fishes 

 imprint the wet sand over which they swim, leaving marks somewhat 

 resembling reptilian footsteps. His arguments were, however, dissented 

 from by other members. The quadrupedal arrangement of the Penn- 

 sylvania foot-prints was again adduced by Professor Rogers, in evi- 

 dence that these, at least, could not have been left by worms, nor even 

 by fishes. 



