314 ANNUAL OE SCIENTIFIC DISCOVERY. 



ON THE EXISTENCE OF TRACKS AND TRAILS ON THE ROCKS OF THE 



LOWER SILURIAN. 



THE following description of some supposed reptilian foot-prints from 

 the oldest rocks of the Lower Silurian series, is taken from the appendix 

 of Sir Charles I/yell's address before the Royal Geological Society of 

 England. He says : 



" We are indebted to Mr. Logan, now at the head of the Govern- 

 ment Survey in Canada, for having carefully determined the position 

 of the rocks containing them. The locality is the village of Beauhar- 

 nois, on the south side of the St. Lawrence, twenty miles above Mont- 

 real. The rock, a fine-grained whitish sandstone, quarried for build- 

 ing, belongs to the group called the Potsdam sandstone of the New 

 York system, and lies at the base of the whole fossiliferous series of 

 North America. Assuming the Chelonian origin of these foot-prints, 

 they constitute the earliest indication of reptile life yet known ; and 

 are not only anterior to the most ancient memorials of fish hitherto 

 detected, but agree in date with the first known signs of well defined 

 organic bodies, such as Linguke, met with in the same rock. Prof. 

 Owen has examined a slab of sandstone, on the upper surface of which 

 the foot-prints are impressed, together with a plaster cast of the re- 

 mainder of the continuous trail, in all 12 feet long, brought to London 

 by Mr. Logan." The following description of these impressions is given 

 by Mr. Owen : " The impressions are more numerous in regular suc- 

 cession than any that have been previously discovered ; so that the evi- 

 dence of their having been made by successive steps, afforded by this 

 succession of corresponding prints at regular intervals, is the strongest 

 we possess. They are in pairs, and the pairs extend in two parallel 

 lineal series, with a groove midway between the two series. The outer 

 Impression of each pair is the largest, and it is a little behind the inner 

 one. Both are short and broad, with feeble indications of divisions 

 at their fore part. They succeed each other at intervals much shorter 

 than that between the right and the left pair. The median groove is 

 well defined, and slopes down more steeply at its sides than towards 

 the bottom, at some parts of the track. I conclude, from these 

 characters, that the animal which loft the track was a quadruped, with 

 the hind feet larger and wider apart than the fore feet ; with both hind 

 and fore feet very short, or impeded by some other part of the animal's 

 structure from making any but short steps ; that the fore and hind 

 limbs were near each other, but that the limbs of the right and those 

 of the left side were wide apart ; consequently, that the animal had a 

 short but broad trunk, supported on limbs either short or capable only 

 of short steps ; and that its feet were rounded and stumpy, without 

 long claws. As to the median impression, that may be due either to 

 a thick heavy tail, or to the under surface of the trunk dragged along 

 the ground. The shape of the body and the nature of the limbs, indi- 

 cated by the above described characters of the steps, accord best with 

 those of the land or fresh-water tortoises ; and the median groove 

 might have been scooped out by the hard surface of a prominent plas- 



