282 On the Track of an Animal lately found 



the sea to which it belonged. These localities are St. Ann, Yau- 

 dreuil, Presqu'ile, Lachute, and St. Elizabeth, and they were 

 last year observed in the neighbourhood of Perth. In the last 

 locality they are associated with a new and remarkable description 

 of track for the discovery of which we are indebted to my friend 

 Dr. James Wilson of Perth, who sent me specimens of it in the 

 month of November last. 



The largest of the specimens was between two and three feet 

 long by a foot wide, and the track upon it so singular that I 

 became desirous of obtaining a greater extent of the trail. For this 

 purpose, in the beginning of Deccember, I sent Mr. Richardson 

 to Perth, where he was guided to the quarry by Dr. Wilson, and 

 shewn the bed in which the tracks occur. The quarry, of which the 

 strata are nearly horizontal, is about a mile from the town, and with 

 the aid of Mr. Glyn, the proprietor, Mr. Richardson obtained in 

 fragments, a surface which measures about seventy-six square feet. 

 To obtain this required a good deal of patience, for there was half 

 a foot of snow on the ground, and from under this it was necessary 

 to remove between two and three feet of rock in order to reach the 

 bed The rock is a fine grained white sandstone similar to that 

 in which the Protichnites occurs at Beauharnois, and of that pure 

 silicious character which is so well known to belong to the Pots- 

 dam formation wherever it is met with. The tracks are impres- 

 sed on a bed which varies in thickness in different parts from 

 one eighth of an inch to three inches. When the upper bed 



was removed large portions 

 of the track-bearino; bed 

 came away with it, and it 

 was necessaryto separate the 

 layers. This was done by 

 heating the surface with 

 burning wood placed upon it, 

 and then suddenly cooling it 

 by the application of snow. 

 This of course cracked and 

 destroyed the thin bed with 

 the impressed tracks, but it 

 left the mould of them on 

 the underside of the upper 

 bed, and by plaster casts 

 Pig. 2, One-fifth nat. size. ivom this we have obtain- 



ed the true form of the original racks. 



