46 FOSSIL REPTILIA OF THE LONDON CLAY. 



Genus — Gavialis, Oppel. 

 Gavialis Dixoni, Owen. Tab. X. 



The characters of the genus Gavialis are much more strongly marked than are those 

 which distinguish the Alligators from the Crocodiles, and leave no ambiguity in the 

 conclusions that may be deduced from them. The present interesting addition to the 

 catalogue of British Fossil Reptiles, is due to the discovery in the Eocene deposits at 

 Bracklesham, by my lamented friend the late Frederic Dixon, Esq., F.G.S., of the remains 

 figured in T. X. The portions of the lower jaw demonstrate, by the slender pro- 

 portions of the mandibular rami (figs. 1, 5), the extent of the symphysis, the uniform 

 level of the alveolar series, and the nearly equal distance of the sockets of the com- 

 paratively small, slender, and equal-sized teeth, the former existence in England, 

 during the early tertiary periods, of a Crocodilian with the maxillary and dental 

 characters of the genus Gavialis. These characters are, however, participated in by 

 some of the extinct Crocodilians of the secondary strata (see T. XI, fig. 2') ; but in 

 them they coexist with a different type of vertebra from that of the recent and known 

 tertiary Crocodilian genera : it became necessary, therefore, to ascertain what form of 

 vertebra might be so associated with the fossil Gavial-like jaws and teeth in the 

 Bracklesham Eocene deposits, as to justify the conclusion that such vertebrae had 

 belonged to the same species as the jaws. Now, the only Crocodilian vertebrae that 

 have yet been found at Bracklesham, so far as I can ascertain, present the proccelian 

 type of articular surfaces of the body (T. X), hke that in Mr. Dixon's collection 

 fig. 8. This vertebra answers to the fifth cervical vertebra in the existing Crocodilians, 

 and accords in its proportions with that in the Gangetic Gavial. There are a few 

 indications of specific distinction ; the parapophysis (p) or lower transverse process 

 articulating with the head of the rib, is relatively shorter antero-posteriorly. The 

 broad, rough, neurapophysial sutures (n) meet upon the middle of the upper part of 

 the centrum ; the elsewhere intervening narrow neural tract sinks deeper into the 

 centrum than in the modern Gavial, but is perforated, as in that species, by the two 

 approximated vertical vascular fissures. The hypapophysis (hs) or process from the 

 inferior surface of the centrum, has been broken off in the fossil, but it accords in its 

 place and extent of origin with that in the fifth and following cervical vertebras of the 

 Gavial. Assuming the fossil proccelian vertebrae from Bracklesham, and the above- 

 described vertebra in particular, to have belonged to the same individual or species as 

 the portions of fossil jaw (figs. 1, 5), then these mandibular and dental fossils must be 

 referred to the genus Gavialis, or to the long-, slender-, and sub cylindrical-snouted 

 Crocodilia with proccelian vertebrae. 



This genus is now represented by one or two species peculiar to the great rivers 

 of India, more especially the Ganges ; and the fossil differs from both the Gavialis 



