A HISTORY OF SUSSEX 



tortoises of this genus are distinguished by the abnormal width of the 

 row of horny shields covering the middle of the back. To a species 

 of an allied genus, Plesiochelys brodiei, typically from the Wealden of the 

 Isle of Wight, is assigned a young shell in the British Museum from 

 the same formation at Hastings ; while fragments of a shell from Cuck- 

 field in the same collection apparently indicate another species of the 

 genus. It should be added that the species to which the names Platemys 

 mantelli and P. dixoni have been applied belong to Hylceochelys belli. 

 Very interesting are certain fragments of a chelonian shell from Cuck- 

 field which have been made the type of a genus and species by the 

 present writer under the name of Archceochelys valdensis ; but they are 

 unfortunately too imperfect for the affinities of the genus to be properly 

 determinated. 



Of long-necked plesiosaurians two small-sized species are known 

 from the Wealden of the county. One of them, Cimoliosaurus llmno- 

 philus, from Cuckfield, was first described from the Wealden strata of 

 the continent. The second, C. valdensis, which occurs at Cuckfield 

 and in the Wadhurst Clay of Hastings, is peculiar to the county. The 

 comparatively small dimensions of both these saurians are probably due 

 to their being dwellers in brackish instead of salt water. 



The fossil fishes of the Sussex Wealden are not numerous, although 

 of considerable interest. Among the pavement-toothed sharks allied 

 to the existing Port Jackson species the widely spread genus Hybodus 

 is represented by H. basanus, a species first described from the Wealden 

 of the Isle of Wight, but which also occurs at Hastings, Hollington, 

 Pevensey Bay and in Tilgate Forest. Teeth from Hastings and Tilgate 

 Forest indicate the occurrence of two other species of the same genus 

 in the Wealden of the county. In the allied genus Acrodus the species 

 A. hirudo was named by Agassiz on the evidence of a tooth, now in the 

 British Museum, from Tilgate Forest ; and the same collection also 

 contains a smaller tooth of this species from the Wealden of Telham 

 near Battle. Fin-spines from Tilgate Forest have been made the types 

 of Asteracanthus granulosus, a species of another widely spread genus of 

 the same group of sharks. 



Among the ganoid fishes, or those whose scales are bony, quad- 

 rangular and highly polished, the button-like teeth of Lepidotus mantelli 

 occur in the Wealden strata of Billingshurst, Brightling, Heathfield, 

 Hastings, Horsham, Tilgate Forest and other localities in the county, 

 often accompanied by scales. In the neighbourhood of Hastings and 

 in Tilgate Forest these teeth are extraordinarily abundant ; they are 

 known to the quarrymen as ' fishes' eyes,' The Wealden species, which 

 also occurs in Germany, was named by Agassiz on the evidence of 

 Mantell's specimens ; many other species of the genus are known from 

 Jurassic and Cretaceous strata. Of the pycnodont ganoids the species 

 Ccelodus mantelli, a member of another widely spread genus, was named 

 by Agassiz from specimens of the dentition collected by Mantell in 

 Tilgate Forest, A second and larger species, C. parallelus, was named 



