Fossils of the Potsdam Sandstone* 35 



Couuty. In both of these localities it is associated with Scolithus 

 linearis. 



" Lingula," Latin, a tongue ; " prima," the fii-st ; " aniiqua,'* 

 ancient. 



3. Fossil Foot-prints. 



The fossils of the Lower Silurian rocks are all of them, so far as is 

 yet known the remains of animals which were confined by their organization 

 to an aquatic life. The mollusks, corals, echinoderms, and trilobites of those 

 ancient formations are all of marine species, but in the Potsdam sandstone 

 which is now considered by some geologists to belong to the Cambrian, 

 there have been found in Canada the tracks of a creature that was 

 o\idently an air breather. Perhaps none of the relics of the tenants of the 

 primeval seas have excited so much interest as these extraordinary and as 

 yet unexplained foot-prints. 



They are so far from resembling anything yet seen in the formations 

 lying im.mediately above, that persons familiar with the fossils of the Chazy, 

 Black-river, and Trenton-limestones can scarcely look upon them without 

 suspecting that they are traces of a type of life that belonged to an age 

 widely disconnected by its organic forms from the Lower Silurian. The 

 Lingulae above figured, it is true, are somewhat similar to species which 

 occur in the Trenton-limestone, but then the fossils of this genus, although 

 ranging through all the formations, do not assist materially in giving a 

 marked aspect to any. We shall here give a short account of the discovery 

 and principal characters of these remarkable impressions. 



In 1847, the late Mr. Abraham, then Editor of the Montreal Gazette, 

 announced in his paper that the tracks of a tortoise had been discovered in 

 the sandstone at Beauharnois. He supposed this rock to be the 

 equivalent of the old red sandstone, and, as previous to the publication of 

 his notice no remains of reptiles had been found in formations of so ancient 

 a date, these were regarded by him as particularly interesting. Mr. 

 Logan's attention was afterwards drawn to the discovery, and he soon not 

 only settled the question as to the geological age of the formation, but also 

 had specimens conveyed to England and laid before the Geological Society 

 of London. Professor Owen, in a short paper, read in April, 1851, before 

 the Society, expressed an opinion that the track was that of a fresh water 

 tortoise, but afterwards having been furnished with other and better 

 specimens, concluded that the creature more probably was an articulated 

 animal, and perhaps a crustacean, the class to which our mode^'n crabs and 

 lobsters belong. The localities where these traces of ancient life have been 

 found in the greatest abundance, are situated in that belt of the Potsdam 

 sandstone which crosses from Lake Champlain northerly to the Ottawa 

 above Montreal. There are here large areas consisting of flat surfaces, like 

 so many floors of rock, on M'hich the tracks are seen winding about, and 

 sometimes crossing each other. Each track consists of two rows of foot- 

 prints, with a groove in the rock, about half way between the rows, as if the 

 animal had dragged something after it. The rows are from four to seven 



