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 



