1862.] MARSH EOSAURUS ACADIANUS. 53 



Batrachian or Amphibian affinities ; and it was observed that, previous 

 to the year 1844, the evidence of even this low form of reptilian 

 life during the Carboniferous period was unsuspected by most geo- 

 logists, and its first appearance upon the earth confidently referred 

 to the Permian epoch. The author gave a short resume of the 

 reptilian remains discovered since that date in rocks of the more 

 ancient period, especially alluding to the joint discoveries of Dr. 

 Dawson and Sir Charles Lyell* and the nidre recent researches of 

 the former geologistf . 



The remains which form the subject of the present communica- 

 tion consist of two centra, or bodies of vertebrae, which were discovered 

 by the author in August 1855. Their resemblance in form and 

 appearance to the vertebrae of Ichthyosaurus was considered by him 

 to be so marked that, at the time of the discovery, he referred them 

 to that genus. A subsequent and more careful examination and 

 comparison, though it confirmed his idea of their Enaliosaurian 

 character, showed some important differences; consequently, as 

 every endeavour to procure further remains met with no success, he 

 proposed for the fossil the name of Eosaurus Acadianus in a short 

 notice which appeared in the ' American Journal of Science ' for 

 March 1862, N. S., vol. xxxiii. p. 278. In a subsequent number of 

 the same journal a full description was given, illustrated with figures 

 and microscopic sections of the vertebrae. 



Locality whence the fossil was obtained. — The fossil was found at 

 the South Joggins, in Nova Scotia, on the southern shore of the 

 Chiegnecto Channel, a branch of the Bay of Fundy, in a bed of 

 argillaceous, chocolate-coloured shale, which forms part of group 

 xxvi. in the elaborate section of this formation made in 1852 by Sir 

 Charles Lyell and Dr. J. W. Dawson. 



Mr. Marsh then gave some stratigraphical details respecting the 

 coal-measures of this locality, noting the more fossiliferous beds and 

 the principal organic remains found in them. 



Osteological description. — The vertebrae, as already stated, are two 

 in number, and when discovered were attached to each other J. Their 

 uniformity in size and appearance, as well as their collocation when 

 found, would indicate that they belonged to the same animal, and 

 were contiguous in the vertebral column. They are remarkably 

 well preserved, a result of their complete ossification in their natural 

 state, and of their being imbedded in the peculiar matrix which has 

 since contained them, and furnished the material for their minerali- 

 zation. The posterior vertebra, in fact, with the exception of a small 

 fracture, seems to be nearly as perfect as in its original condition ; 

 and from it the description and measurements given § were mainly 

 taken. 



A detailed account of the osteological characters of the fossil was 

 then given, and the points in which it agrees with, or differs from, 



* Quart. Journ. Geol. Soc. vol. ix. p. 58. t Op. cit. vol. xvi. p. 273. 



| See Am. Journ. Science, pi. 1. figs. 1 & 2, n. s., vol. xxxiv. 

 § Op. cit. p. 4, &c. 



