﻿WEALDEN FORMATIONS. 



7 



in the present species, from the fore part or end of the premaxillary, and are directed 

 forward with a slight downward curve. 



In a still larger species {Criorhynchus simus 1 ), from the Upper Greensand of 

 Cambridge, the foremost pair of teeth project from the under surface of the fore end of the 

 premaxillary, and are directed downward like the following teeth. The fore end of the 

 premaxillary was fortunately entire, showing a flattened or feebly concave tract corre- 

 sponding to the part bored by the anterior alveoli in Coloborhynchus. Some reserve may 

 be prudently entertained as to whether a pair of teeth so anomalously located as in 

 Coloborhynchus might not be shed without replacement by successors ; and the genus 

 Criorhynchus is to be accepted with this reserve, which future discoveries may dissipate. 

 The manifestation by a ' truncirostral ' Pterodactyle of the Wealden, and by another 

 from the 'Greensand,' of the produced and unopposed pair of teeth from the front surface 

 of the muzzle, have dissipated the doubts as to its accidental and individual character which 

 legitimately attached to the first specimen, from the Chalk, in which it was observed. 



Coloborhynchus clavirostris is, at present, represented by the fore part of the upper 

 jaw of a Pterodactyle (PI. I, figs. 1 — 4) from the Wealden, of equal size with Crio- 

 rhynchus simus, from the Upper Greensand, but in which the small anterior pair of 

 premaxillary teeth project from the front surface of the bone, and at a greater elevation 

 above the palate and the sockets of the second pair, than in Coloborhynchus Cuvieri or 

 Colob. SedywicJcii. 



The flattened fore part of the premaxillary (ib., fig. 2) is broader and of less height in 

 Coloborhynchus clavirostris before the narrow upper surface begins to slope backward 

 to the upper contour of the cranium. The anterior median depression (^) is shorter 

 vertically and deeper in Colob. clavirostris, where it is below the alveoli of the teeth («,«). 

 The convexities (j, j) on each side of this depression are the fore parts of the sockets of the 

 second pair of teeth, not of the first pair, as in Criorhynchus simus (Monog. cit., PL I, 

 fig. 3, a). The sides of the fore part of the premaxillary in Coloborhynchus clavirostris 

 converge, with a slight vertical concavity, to the narrow but obtuse upper border of the 

 skull ; the same sides also converge as they recede in a slighter degree, but so that the 

 breadth of the upper jaw behind the sixth pairs of teeth (ib., figs. 1 and 4,/,/) is less 

 than two thirds the breadth behind the second pair of teeth (ib., b, b, fig. 4), whence the 

 name clavirostris (' club-snout ') proposed for the present formidable species of Wealden 

 Pterodactyle. 



The fore part of the bony palate, between the teeth of the second pair (ib., fig. 4, b, b), 

 is transversely quadrate and flat (ib., fig. 4, Behind this tract the mid third only 

 of the palate retains its level, the two side thirds subsiding (as it seems when looked 

 down upon) into shallow channels, which expand and are continued into the slope rising 



1 Ib., ib., 4to, Supplement No. Ill to • Monograph on the Fossil Reptilia of the Cretaceous Formations,' 

 Pterosaubia, p. 2, PL I (Palaeontographical Society's volume for year 1858). 



