REPTILIAN REMAINS. 



119 



A very interesting fossil, which greatly aids in fixing this geological 

 age for the red sandstones of Prince Edward Island, has recently 

 been discovered. It is a portion of the jaw of a large carnivorous 

 reptile, apparently closely allied to the Thecodontosaurus of the 

 English New Red Sandstone. This creature must have rivalled in 

 dimensions the modern alligators, but must have belonged to a differ- 

 ent group of reptiles, represented in the present world only by lizards 

 of moderate or small dimensions. It was, in short, one of that giant 

 reptile aristocracy which constituted the dominant animal type in the 

 Middle or Secondary period of geological time, which in consequence 

 has long been known as the peculiar " age of reptiles." 



The specimen was found by Mr D. M'Leod of New London, on 

 the north side of the island, in the bottom of a well, at the depth 

 of twenty-one feet nine inches, and imbedded in the ordinary soft red 

 sandstone of that part of the island. The discoverer was desirous 

 of disposing of the specimen ; and the writer being convinced that 

 it would prove of great interest to naturalists, if examined and 

 described by a competent anatomist, offered to negotiate its sale. 

 By the advice of Sir Charles Lyell, then in America, it was offered 

 to the Academy of Natural Sciences, Philadelphia ; for which it was 

 finally purchased for the sum of thirty dollars. It was described and 

 figured in the Proceedings of the Society by Dr Leidy, from whose 

 elaborate paper I extract the following description, which, with the 

 aid of Fig. 29, will serve to give some idea of its character : — 



Fig. 29. — Outline of Jaw of Bailiygnatlms borealis, — reduced. 



o^ 



(a) Cross section of second Tooth, nat. size. 



{b) Fifth Tooth, nat. size. 



" The specimen consists of the right dental bone, considerably 

 broken, attached by its inner surface to a mass of matrix of a red 

 granular sandstone, with large, soft angular red chalk-like stones 



