WEALDEN PTERODACTYLES. 539 



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

 part as Pterodacfi/Ius saffittirosfris. 



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

 Pterodactyle as in the Oolitic loiigirostral species.^ 



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

 characters of Cuvier's genus Pterodacti/lus has led to its subdivision into several groups 

 or subgenera. 



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

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

 go to a different group from that including the Pter. longiroslris? 



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

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

 Pampliorhynchis 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 Cuvierian genus Pterodactylus. 



The most striking characteristic difference from that species is the vastly superior size 

 of the seemingly allied Flying Dragons from the British Chalk and Wealden. 



In the restoration of the skull of Plerodadylm compressirostris (pp. 234 — 252, 

 Pis. 1 — 5) I ventured to assign to the mandible a length of 14 inches 9 lines 

 {Pter., PI. 1, fig. 5). This species was represented by two portions of the upper 

 jaw from the Middle Chalk of Kent, the longest portion being 4 inches in length. Of 

 the nearly allied species, represented by three portions of the lower jaw, discovered by 

 Samuel H. Beckles, Esq., F.R.S., F.G.S., in the Hastings series of the Wealden 

 Formation, west of St. Leonard's-on-Sea, the restoration figured of half the natural size in 

 PI. 18, fig. 8, gives a mandible of between 14 and 15 inches in length, and this on the 

 most moderate estimate of the length of the symphysis. In a sketch of a restoration of 

 the jaw, sent to me with the fossils by Mr. Beckles, the length of the symphysis, which 

 he assigns on the basis or analogy of that in CoUins's or Cuvier's Plerodadyhm hngirostris, 

 gives a total length of 18 inches to the mandible. 



The parts obtained by Mr. Beckles are of one and the same lower jaw ; and, as an 

 extent of above 2 inches of both rami are maintained by a portion of matrix (ib. ib., 



1 Cuvier, torn, cit., p. 3G4. 



2 II)., ib. 



3 In which Cuvier describes the tail as " trcs-courte, trfes-grele, et Ton n'y compte que iloiize ou treize 

 vert^bres." — Tom. cit., p. 368. 



