PALEONTOLOGY Large conical fluted teeth from the Chalk of Falmer, Glynde, Lewes and Steyning belong to the huge reptile named Polyptychodon interriiptus, which is a near ally of the better known Jurassic genus P/iosaurus, itself a large-headed and short-necked member of the group of marine saurians termed Plesiosauria. A tooth from Houghton in the Brighton Museum has been assigned to a second species of the former genus, Polyptychodon contitmus. The Brighton Museum also contains remains of long-necked plesiosaurians from the Chalk of Clayton, Lewes, Houghton, Scellescomb and Southeram, which may be provisionally assigned to the Cretaceous genus Cimoliosaiirus. To this type belong the plesiosaurians from the Sussex Chalk described by Owen under the names of Pksiosaurus bernardi and P. constrictus. Two imperfectly known turtles complete the list of reptiles described from the Sussex Chalk, One is indicated by portions of the shell and vertebrae from Lewes and Clayton in the British and Brighton Museums, which are tentatively assigned to the typical genus Cheloiie. The other is represented by an imperfect bone (the humerus) in the British Museum from Lewes, referred to a species of leathery turtle, Protostega anglica, typified by a bone from the Cambridge Greensand. The fishes from the Sussex Chalk number more than seventy, out of which over forty species were named on the evidence of speci- mens found in the county. Commencing with the rays, the first to be mentioned is a species of angel-fish, Squatina cranei, named by Dr. Smith Woodward in 1888 on the evidence of a unique specimen from Clayton in the Brighton Museum. The pavement-like teeth of the rays of the extinct genus Ptychodus are comparatively common in the Chalk of the county, and have been assigned to six species, of which all but the first and last were named from Sussex examples. Of these species P. mammillaris is recorded from Glynde and Lewes, P. rugosus from Arundel and elsewhere, P. oiveni from Lewes, P. decurrens from Brighton and Lewes, P. polygyrus from Lewes and Seaford, and P. latisshnus from Lewes. Nearly perfect sets of the dentition of the last-mentioned species and P. decurrens are preserved in the Brighton Museum. Of the existing comb-toothed sharks the common Cretaceous Notidanus microdon has been obtained at Brighton, Lewes and Newtimber. Among sharks with crushing teeth allied to the living Port Jackson Cestracion philippic and included in the same family, Synechodus illingioorthi was described by Dixon ' from teeth obtained in Southeram pit near Lewes ; while a tooth from Glynde is provisionally assigned to S. dubrisiensis, of which Dover is the type locality. Neither are species referred to the same genus as the Port Jackson shark absent from the Chalk of the county, remains of Cestracion canalkulatus having been obtained from Southeram, and of C. rugosus from Lewes. Special interest attaches to the occur- rence in the Chalk of the county of remains of a species of beaked shark, Scapanorhynchus rhaphiodon^ since this genus was long supposed to be extinct, but has been recently discovered living in Japanese waters. Of 1 As Acrodus. 31
