ON BRITISH FOSSIL REPTILES. 73 



characterized by a combination of a biconcave structure of the vertebrag, with 

 long, narrow jaws, armed with slender, conical, sharp-pointed and equal teeth, 

 adapted, liiie those of the existing Gavials, for the seizure and destruction 

 of lishes. The species are separated into two genera, according to the 

 difference of position in the external nostril, which, in the one called Teleo- 

 suMviis, is terminal, or at the extremity of the upper jaw; in the other, 

 called Steneosaurus, is a little behind and above the termination of the 

 upper jaw. The species of both genera are confined to the oolitic division 

 of the secondary rocks, and, since there were scarcely any Mammalia during 

 that period, whilst the waters were abundantly stored with fishes, it might, a 

 priori, have been expected, Dr, Buckland justly observes, "that if any Cro- 

 codilian forms had then existed, they would most nearly have resembled the 

 modern Gavial*." The modification in tlte structure of the vertebral column, 

 and their complete mail of imbricated bony scutes, also indicate that the 

 habits of the ancient Teleosauri and Steneosauri were more strictly marine 

 than are those of the modern Gavials, and that their powers of swimming, of 

 pursuing and overtaking their aquatic prey, were greater. 



The extinct reptile from which the characters of the genus Telcosaurus 

 are derived, is one of the earliest of the evidences of ancient Reptilia which 

 is recorded in a scientific publication. A brief description, and figures of an 

 incomplete skeleton found in the lias (alum schale) of the Yorkshire coast, 

 about half a mile from Whitby, were published by Messrs. Wooller and 

 Chapman, in two separate communications, in the 50th volume of the Philo- 

 sophical Transactions, 1758, (Pt. 2, jil. xxii. and xxx.). Their figures ex- 

 hibit a contorted and incomplete vertebral column, about nine feet long, and 

 a cranium slightly displaced, two feet nine inches in length. About ten ver- 

 tebrae of the lumbar and sacral region of the trunk, and twelve vertebrae of 

 the tail remain in place ; the cervical, dorsal, and middle coccygeal vertebrae 

 were indicated only by their impressions ; and these are fewer in number 

 than the vertebrae in the existing Crocodiles. The skull is reversed, pre- 

 senting its basal surface to view : the single occipital condyle, the zygomatic 

 arches, terminated behind by the strong tympanic bones, and the lai'ge convex 

 articular surface in each of these, for the lower jaw, placed in the same trans- 

 verse line as the occipital condyle, are all recognizable. The skull appears to 

 contract gradually to a pointed muzzle, but in reality to the base of a long 

 and slender maxillary beak. In the remaining basal or posterior portions of 

 the jaws, the sockets of the teeth are seen separated by intervals of about 

 nine lines ; in some of these there are pointed conical teeth, which cross al- 

 ternately those of the opposite jaw. The teeth are covered with polished 

 enamel f. 



Each of the vertebrae is three inches in length. Near the pelvic region, the 

 .shaft of the femur, including the head, was exposed, measuring between 

 three and four inches in length. A few fragments of ribs were found near 

 the dorsal vertebrae. The authors of the papers just analysed perceived suf- 

 ficient resemblance between their fossil and the skeleton of the Crocodile to 

 refer it to that family of reptiles + ; but their figures and descriptions gave rise 

 to various opinions respecting the affinities of the Whitby fossil in the writings 



* Bridge-water Treatise, vol. i. p. 250. 



t Cuvier truly states, " Ellcs n'ont pas cte decrites particiilicrement, et il est impossible 

 de juRcr de Icurs caractcrcs par la gravure." — Oss. Fbss. 183G, ix. 225. 



X Captain Chapman says, " It seems to have been an alligator;" (/. e., p. 691.) and Mr. 

 Wooller thinks that " it resembles in every respect the Gangetic Gavial." It will be shown, 

 however, that the fossil really differs more from the Gavial than the Gavial does from any 

 other exiatiug Crocodilian, 



