122 THE TRIAS OR NEW RED SANDSTONE. 



activity. Without these nothing very certain can be determined on 

 these subjects. The apparent thinness and density of the bone, 

 however, and its width of surface, convey the impression that it was 

 intended to combine great strength with great lightness, and therefore 

 that it belonged to a creature of terrestrial habits. Probably con- 

 siderations of this kind, though he does not state his reasons, induced 

 Dr Leidy to hazard the conjecture, " Was this animal probably not 

 one of the bipeds which made the so-called bird-tracks of the New 

 Red Sandstone of the valley of the Connecticut? " This conjecture of 

 an eminent anatomist, itself shows how .singular and anomalous among 

 reptiles is this fossil fragment. 



Had this fossil been specifically identical with any reptile whose 

 remains have been found in other countries the age of whose rocks 

 has been determined, it might have given conclusive evidence as to 

 the true geological age of the red sandstones of New London. It is, 

 however, a new species of a new genus, quite distinct therefore from 

 any species found elsewhere. Still it gives some important testimony. 

 It belongs to a group of large and highly organized carnivorous 

 reptiles now extinct, and which occupied in the Secondary period of 

 geology a place afterwards taken by the carnivorous mammalia. No 

 reptiles of equal grandeur and perfection have existed since the 

 beginning of the Tertiary period ; and so far as we know, none were 

 created before the very close of the Palaeozoic period. Between these 

 eras, therefore, we may place our fossil ; but this gives a very wide 

 range. There is, however, a difference of fades or general appearance 

 between the reptiles of different parts of this long reptilian dynasty, 

 which enables us to distinguish between them, just as an antiquary 

 might distinguish a coat of armour of the time of John of Gaunt from 

 one of the time of Henry the Seventh. Now, as already hinted, the 

 reptile in question appears to have most nearly resembled the Theco- 

 do7itosaurits and Palceosaurus, reptiles of the Triassic system of 

 England, than any other known animals; hence it confirms the view 

 generally adopted on other grounds, that this is the age of the Prince 

 Edward Island New Red, and its corresponding formation in Nova 

 Scotia. At the time when the first edition of this work was published, 

 it was held by British geologists that the dolomitic conglomerates of 

 Bristol, in which the remains of the two saurians above named are 

 found, belonged to the Permian period ; and I stated accordingly 

 that the affinities of Bathygnathus seemed to be with reptiles of that 

 period. More lately, however, the officers of the Geological Survey 

 of Great Britain have satisfied themselves that the beds in question 

 belong to the Trias. 



