ON FOSSIL AND RECENT REPTILIA. 163 



anterior ; and in them we have the earliest manifestation of the ' proccelian ' 

 type of vertebra. 



The Ptorosauria are distributed into genera according to modifications of 

 the jaws and teeth. In the oldest known species, from the Lias, the teeth are 

 of two kinds ; a few, at the fore part of the jaws, are long, large, sharp- 

 pointed, with a full elliptical base, in distinct and separated sockets : behind 

 them is a close-set row of short, compressed, very small, lancet-shaped teeth. 

 These form the genus Dimorphodon, Ow. 



In the genus JRhamphorhynchus, V. M,, the fore part of each jaw is without 

 teeth, and may have been encased by a horny beak ; but behind the edentulous 

 production there are four or five large and long teeth, on each side, fol- 

 lowed by several smaller ones. The tail is long, stiff, and slender. 



In the genus Pterodactylus, Cuv., the jaws are provided with teeth to their 

 extremities : all the teeth are long, slender, sharp-pointed, set well apart. 

 The tail is very short. 



The Pter. longirostris, Ok., was about 10 inches in length ; it is from litho- 

 graphic slate at Pappenheim. The Pter. crassirostris, Goldf. was about 1 foot 

 long ; but the Pter. Sedgwichii, Ow., from the greensand, near Cambridge, 

 had an expanse of wing of 20 feet. The above species exemplify the Ptero- 

 dactyles proper. 



The oldest well-known Pterodactyle is the Dimorphodon macronyx, of the 

 lower lias ; but bones of Pterodactyles have been discovered in coeval lias 

 of Wirtemberg. The next in point of age is the Dimorphodon Banthensis, 

 from the 'Posidonomyen-schiefer' of Banz in Bavaria, answering to the Alum- 

 shale of the Whitby lias. Then follows the Pt. Bucklandi from the Stonesfield 

 oolite. Above this, come the first-described and numerous species of Ptero- 

 dactyle from the lithographic slates of the middle oolitic system, in Germany, 

 and from Cirin on the Rhone. The Pterodactyles of the Wealden are, as yet, 

 known to us by only a few bones and bone-fragments. The largest known 

 species are the Pterodactylus Sedgwickii and Pter. Fittoni, from the Upper 

 Greensand of Cambridgeshire. Finally, the Pterodactyles of the middle 

 chalk of Kent, almost as remarkable for their great size> constitute the last 

 forms of Flying Reptile known in the history of the crust of this earth. 



Order VII. Thecodontia*. 



The vertebral bodies are biconcave : the ribs of the trunk are long and 

 bent, the anterior ones with a bifurcate head : the sacrum consists of three 

 vertebras: the limbs are ambulatory, and the femur has a third trochanter. 

 The teeth have the crown more or less compressed, pointed, with trenchant 

 and finely serrate margins ; implanted in distinct sockets. 



Teeth of this type, which may have belonged to the loricated saurian 

 Stagonolepis, have been discovered by Mr. P. Duff in the white-sandstone at 

 Lossiemouth near Elgin, affording additional evidence of its triassic age. 



The Protorosaurus of the Permian Kupferschiefer of Thuringia appears 

 to have had its teeth implanted in distinct sockets; but the neck-vertebrae 

 resemble in their large and strong proportions those of the Pterodactyles ; 

 and the caudal vertebrae show the peculiarity, among Reptiles, of bifurcate 

 neural spines. The types of the present order are the extinct genera Theco- 

 dontosanr'is and Palceosaurus of Riley and Stutchbury, from probably triassic 

 strata near Bristol ; and the Cladyodon of the New Red sandstone of Warwick- 

 shire, with which, probably, the Belodon of the Kcupcr Sandstone of Wir- 

 temberg is generically synonymous. The Bathygnathus, Lcidy, from New 

 Red sandstone of Prince Edward's Island, North America, is probably a 



* O/'iKr}, a case ; otWs, a tooth. 



M 2 



