Page:VCH Sussex 1.djvu/75

 PALAEONTOLOGY was named by Dixon Phacodus punctatus, the type specimen, now in the British Museum, being from Lewes. A group of five teeth from Lewes in the British Museum has been made the type of a genus and species, with the name Acrotemnus faba. Another group of extinct ganoids — the Eiignathidce — are repre- sented in the Chalk of Alfriston and Lewes by Lophiostomus dixoni, the only other species of the genus occurring in the Cambridge Greensand. In a third family, the Pachycormida, we find the spear-like teeth of the widely spread but still imperfectly known Protosphyrana ferox (often incorrectly called Saurocephalus lanciformis) in the Chalk of Amberley, Glynde, Lewes and Newtimber ; a second species of the same genus, P. minor, was named from a Lewes specimen. In yet another extinct ganoid family, the Aspidorhynchidce, the species Belomstomus ductus was described by Agassiz on the evidence of a specimen from Lewes ; another specimen from Southeram, now in the Brighton Museum, was named B. attenuatus, but its right to distinction is doubtful. With the species known as Elopopsis crassus, named by Dixon (as Osmeroides) from a specimen in the Brighton Museum from Mailing, Kent, but also known from Southeram, we come to a more modern type of fish, allied to the herrings. Another member of the same family [Elopida] is Osmeroides lewesiensis, which, as indicated by its name, was described on the evidence of a Lewes fossil ; a second species, 0. levis, has been recently described by Dr. Smith Woodward,^ the type being from Kent, but another specimen from the Lower Chalk of Lewes. The same writer" has also described a Lewes ' ichthyolite ' as Thrisso- pater (?) megalops, an undoubted member of the same genus, 'T. magnus, also occurring in the Chalk of the county. The fishes of this genus belong to the Elopidce, and are probably ancestral types of the modern herrings. To the same family probably belongs the genus Pachyrhizodus, of which the species P. basalis, P. gardneri, and P. siibulidens occur in the Chalk of the county, although neither is based on Sussex specimens ; the third species was originally described as Rhaphiosaunis on the evidence of its teeth, which were believed to be those of a lizard. A fourth fish, from Glynde and Southeram, has been described as Protelops anglicus, the other species of the genus, which also belongs to the Elopidce, being from the Bohemian Chalk. To the family Osteoglossidce, the existing members of which are restricted to the rivers of the southern hemisphere, or to the allied Albulidce, may be provisionally assigned the fish described by Dixon as Plethodus expatisus on the evidence of a dental plate from Kent now in the Brighton Museum, this species being probably also represented in Sussex ; a second species, P. oblongus, is typified by another dental plate from Clayton in the same collection ; while a third, P. pentagon, first described from Kent, also occurs in the Sussex Chalk. Large teeth from Lewes have been provisionally assigned to the genus Portheus, which occurs typically in the Cretaceous strata of North America, and » Cat. Foss. Fish. Brit. Mus. iii. i6 (1901). ^ ibid. p. 3;. I 33 5