156 REPORT — 1S41. 



Order PTEROSAURIA. 



The term Ornithocephalus, originally imposed by Soemmering on the genus 

 Pterodactjjlus, Cuv,, which is the typo of the present extinct order of reptiles, 

 would be much more applicable to the RJti/nchosaurus ; for although a more 

 striking approach to the class of birds is made by the modification of the 

 pectoral extremity which endowed the Pterodactyle with the power of flight, 

 it is precisely in the structure of the cranium that it adheres most closely to 

 the ordinary Saurian type of structure. 



The genus Pterodactylus was ranked among the swimming-birds by Blu- 

 menbach, with the clieiropterous Mammalia (Bats) by Hermann and Soem- 

 mering, and has been proved to belong to the order of Reptiles by Cuvier, 

 The Pterodactylus longirostris, from the lithographic slate of Pappenheim, 

 was the earliest known species ; the Pter, hrevirostris, Pter. medius, and Pter. 

 grandisy were next established, and subsequently the British species Pter. ma- 

 cronyx was determined by Dr. Buckland, from remains discovei'ed in the lias 

 of Lyme Regis, and which, before they came under the discriminative glance 

 of the Oxford Professor, had passed as the bones of birds. 



Of this species Dr. Buckland describes the principal bones of the extremi- 

 ties, and several vertebrae ; the cranium has not yet been discovered. The 

 valuable subject of th^ Professor's memoir is deposited in the British Mu- 

 seum ; the Memoir is contained in the thii'd volume of the second series of 

 the Transactions of the Geological Society, and an accurate figure of the 

 specimen is given, of the size of nature, at plate xxvii.* 



A second stratum, in which the remains of Pterodactyles have been de- 

 tected by Dr. Buckland, is the oolite slate of Stonesfield. Some fine speci- 

 mens of the lohg bones of the extremities of Pterodactyles from that locality, 

 in the collection of John Hunter, were referred by that celebrated anatomist 

 to the class of birds. 



Sauria IncertjE Sedis. 



Pohjptychodon. — A large species of Saurian is indicated by thick conical 

 teeth, having the general character of those of the Crocodile, but distin- 

 guished by numerous, closely-set, longitudinal ridges, M'hich are continued, of 

 nearly equal length, to within 2 lines of the apex of the crown. These teeth 

 have been described and figured in my ' Odontography' under the name of 

 Pohjptycliodon. In their size and general form these Saurian teeth resemble 

 those of the great sauroid fish, Hypsodon, Ag., but may be distinguished by 

 the solidity of the crown, and the conformity of the structure of the dentine 

 with tliat of the Crocodiles ; also by the ridges on the exterior of the crown 

 of the Hypsodon's teeth being alternately long and short, and terminating 

 abruptly at difierent but commonly greater distances from the apex than in 

 PolyjJtychodon, the interspaces between the longer ridges widening as they 

 approach the apex. The tooth of the Pohjptychodon is slightly and regu- 

 larly curved, and invested Avith a moderately thick layer of enamel, of which 

 substance the ridges are composed, the surface of the outermost layer of den- 

 tine being smooth. A tooth of this reptile from the lower greensaud 

 (Kentish-rag quarries) near Maidstone, in the collection of Mr. Benstead of 

 that townf, has a crown 3 inches long, and 1 inch 4 lines across the base. 

 The compact dentine is resolved by decomposition into a series of super- 

 imposed thin hollow cones, and the short and wide conical pulp-cavity is con- 



* See also the interesting cliaptw on " Flying Saurians'' in the 'Bridgewater Treatise,' 

 vol. i. 1). 221. 



t Presented by that gentleman, since the reading of this Report, to the Museum of the 

 Royal College of Surgeons. 



