TRANSACTIONS OP THE SECTIONS. 79 



Notice of the Discovery of Ichthyosaurus and other Fossils in the late 

 Arctic Searching Expedition, 1852-54. By Captain Sir Edward 

 Belcher, CB. 



The position where the remains of the Ichthyosaurus were found on the summit 

 of Exmouth Island, about 700 feet above the sea-level, is in lat. 77° 16' N., and 

 long. 96° W. The upper stratum of limestone is about 30 feet in thickness, 

 dipping at an angle of 7° westerly. The inferior stratum is of red sandstone of 

 a deep red colour, which gave to the island, in the first instance, the name of Red 

 Island. 



The base of the island is of a friable disintegrating sandstone, which has been 

 worn away on all sides, leaving the concentric elevation equal to one-third of its 

 original diameter, and rising so abruptly from its base as to be accessible only on 

 its western end. 



These fossils were examined by Professor Owen, and described as follows: — 



" The specimens submitted to me by Captain Sir Edward Belcher, which form 

 the subjects of plate 31, are fossil remains of vertebrae and portions of ribs of an 

 Ichthyosaurus. 



" Figs. 1, 2, and 3 represent the largest and best preserved fossil, which is the body 

 of an anterior abdominal vertebra. It presents the ichthyic character of the con- 

 cavity of the articular surface on both the front and back part of the centrum c ; with 

 the character of co-existiug diapophyses d and parapophyses f, not known in fishes, 

 but which the Enaliosauria present in their anterior trunk-vertebrse, in common 

 with the Binosauria, Crocodilia, and other highly organized reptiles. The generic 

 characters of the Ichthyosaurus are manifested in the shortness {i. e. the relatively 

 small fore and aft diameter) of the centrum as compared with its breadth and height, 

 and in the shape of the neurapophysial surfaces n p, and their proportions to the 

 free neural surface n. With regard to the specific character of this vertebral cen- 

 trum, its proportions pretty closely accord with those of the Tchthyosaurus acutus 

 from the Whitby lias ; but this would be quite inadequate ground for a reference of 

 the Arctic Ichthyosaur to that species in the absence of any evidence of the shape 

 of its skull and dentition. 



" Figs. 4 to 7 are of a terminal caudal vertebra, of the natural size, apparently of 

 the same species of Ichthyosaur and probably from the same individual as the ver- 

 tebrae figs. 1-3, from the more advanced part of the body. 



" The small caudal vertebra equally manifests the Ichthyosaurian characters in its 

 degree of biconcavity and in the form of the neurapophysial pits np; the lateral 

 compression of the centrum indicates the vertebral development of the tegumentary 

 tail-fin it helped to support : on the under surface are four surfaces for the haemal 

 arches, which are articulated, as in the Crocodiles, at the vertebral interspaces to 

 two contiguous centrums. 



" Figs. 8 to 11 are portions of ribs. The long, free, thoracic-abdominal pleurapo- 

 physes, or vertebral ribs, of the Ichthyosaurus are peculiar for the deep longitudinal 

 groove which impresses them on each side, giving to their transverse section the 

 form represented in fig. 10. Two fragments of ribs, figs. 8 and 9, found associated 

 with the before-described vertebrae, present this grooved character, and, with the 

 vertebrae, aiford cumulative proof of the Ichthyosaurian nature of the Arctic fossils 

 represented in plate 31*." 



It was on the centre of the island, at its highest pitch, and at a vertical blufF 

 where a cairn was constructed, that these remains, accompanied by other fossils, 

 were noticed ; and at the last moment, on finishing the pile, two specimens were 

 presented by one of the men, apparently fossil bones ; but, from anxiety to proceed 

 and save the season, were hastily thrust into the pocket, and consigned, with others, 

 for future scrutiny. 



It is remarkable that no fossiliferous limestone is met with on the westernmost 

 cliff of Exmouth Island, nor on any of the lands outside of an oval space which 

 would include Princess Royal Island, and the cliffs adjacent— on an axis of twenty- 

 five miles ; nor do any further traces of fossils of any description re-appear until 



* Impressions of the Plates referred to were presented to the Association. 



