Page:VCH Sussex 1.djvu/72

 A HISTORY OF SUSSEX interesting to note the occurrence at Bracklesham of a species, Arius egertoni, belonging to an existing tropical genus, this species also occur- ring in the Belgian Eocene. Among the mackerel family [Scombrida) remains of an undetermined species of the extinct genus Scotnbrhamphodon occur at Bracklesham, and these deposits have likewise yielded specifically indeterminable vertebrae referable to the genus Xiphiorhynchus, an extinct type of sword-fish. Another Bracklesham sword-fish, Histiophorus eoccentcus, belonging to a genus still living, has been recently named by Dr. Smith Woodward on the evidence of a ' sword ' in the British Museum. Lastly, we have Platylcemus colei, an extinct generic type of bass [habridce] described by Dixon on the evidence of specimens of the dental plates from Bracklesham, and at present unknown elsewhere. Dr. Woodward describes it as ' an extinct genus known only by the pharyngeals, each nearly or completely covered by a crushing plate, which consists of coarse vascular dentine invested with a very thin layer of gano-dentine.' The Lower Eocene Bognor beds — the equivalent of the London Clay — seem to be exceptionally poor in vertebrate remains. They have however yielded an imperfect turtle-shell, which was made the type of a species by Owen, under the name of Chelone declivis, although it has since been provisionally identified ^ with one from the London Clay of Sheppey, now known as Argillochelys convexa. Vertebrae apparently referable to the long-nosed Lower Eocene crocodile known as Crocodilus spenceri also occur at Bognor. The reptiles of the Sussex Chalk are not numerous, although some are of considerable interest. The great marine lizards known as Mosasauria are represented by Liodon anceps, a species which also occurs in the Chalk of Norfolk and Essex. A second species of the group has been described on the evidence of remains (now in the Brighton Museum) by Owen under the name of Mosasaurus gracilis. These remains were at one time considered by Dr. Smith Woodward to in- dicate a fish of the genus Pachyrhizodus rather than a reptile, but subse- quent investigation has convinced the same palaeontologist * that the original determination was correct, although it does not follow that the species belongs to the genus Mosasaurus. The crown of another mosasauroid tooth from the Chalk of the county has been provisionally assigned by the present writer ^ to the American Cretaceous genus Platecarpus. The most interesting of the Sussex Chalk lizards is how- ever Dolichosaurus longicollis, a long-necked, snake-like, marine type also occurring in the Chalk of Kent ; in Sussex its remains have been found in Southeram pit, near Lewes. Remains from the Chalk of Washington near Worthing have been regarded as those of a small lizard, under the name of Coniasaurus crassidcns. Another presumed lizard, Rbaphio- saurus subulidens, is now definitely known to have been named on teeth of a fish. ' Cat. Foil. Rcf't. Rill. Mm. Hi. 48. » Cot. Fois. Fish. Brit. Mm. iv. 45. ■■' Cut. Foil. Rr/>t. Brit. Mns. i. 271. 30