﻿WEALDEN FORMATIONS. 3 



§ 2. Pterosauria from the Wealden. 

 A. — Pterodactylus sagittirostris, Owen (Plate II, figs. 1 — 8). 



The type of Cuvier's genus Pterodactylus is the species which he calls longirostris. 

 The chief generic character is the extreme length of the fourth digit of the fore-limb. 1 



The Pterodactylus longirostris, Cuv., is characterised, as the term implies, by long, 

 slender, tapering jaws, armed along their anterior half by numerous long, slender, 

 pointed, separated, and pretty equally distant teeth. 



In a general way the portions of mandible about to be described repeat these 

 characters. The mandibular teeth appear to have been about the same in number. 

 Nineteen are reckoned by Cuvier to have occupied the dentigerous part of each mandi- 

 bular ramus in the type-species ; 2 and about as many appear to have armed the same 

 part as Pterodactylus sagittirostris. 



There is as little trace of condyloid or coronoid processes in the present Wealden 

 Pterodactyle as in the Oolitic longirostral species. 3 



The great and rapid addition to the number of extinct flying Reptiles having the 

 characters of Cuvier's genus Pterodactylus has led to its subdivision into several groups 

 or subgenera. 



If length of tail with number of caudal vertebrse be accepted as a generic character, 

 those that have that appendage long, and supported by more than thirteen vertebrae, must 

 go to a different group from that including the Pter. longirostris. 4 



It is plain that Pter. sagittirostris has not the generic dental characters of Dimor- 

 phodon. It is probable that the symphysial modification which supports the generic name 

 Ramphorhynchus was not present. 



If the skull of the long- and sharp-jawed Wealden species, or of that from the Upper 

 Chalk which I have described under the name of compressirostris, should ultimately be 

 found to offer marked differences in the forms, sizes, and proportions of the narial, orbital, 

 and intermediate vacuities, from those figured by Cuvier in pi. xxiii (op. cit.), it 

 may be deemed requisite to refer them to a distinct pterosaurian group. At present it 

 appears to be convenient to place the sagittirostral and compressirostral with the typal 

 species in the Cuverian genus Pterodactylus. 



1 " Un genre de Sauriens, caracterise par l'excessif allongement du quatrieme doigt de devant, auquel 

 nous avons donne le nom de Pterodactyle." — ' Ossemens Fossiles,' torn, v, pt. ii, 4to, 1824, p. 358. 



2 Cuvier, torn, cit., p. 364. 



3 lb., ib. 



* In which Cuvier describes the tail as " tres-courte, tr&s-grele, et Ton n'y compte que douze ou treize 

 vertebres." — Tom. cit., p. 368. 



