CRETACEOUS FORMATIONS. 97 



In attempting to form a conception of the total length of the head of the very- 

 remarkable species of Pterodactyle, represented by the portions of jaw above described, 

 we should be more justified by their form in adopting the proportions of that of the 

 Pt. longirostris than in the case of the Pt. Cuvieri : but, allowing that the external 

 nostril may have been of somewhat less extent than in the Pt. longirostris, we may 

 still assign a length of from 14 to 16 inches to the skull of the Pterodactyle in 

 question, of which I have attempted an analogical restoration in T. XXVII. 



It could not have been anticipated that the first three portions of Pterodactylian 

 skull, and almost the only portions that have yet been discovered in the Cretaceous 

 Formations, should have presented such well-marked distinctive characters one from the 

 other as are described and illustrated in the present Monograph. Such, nevertheless, 

 are the facts ; and however improbable it may appear, on the doctrine of chances, to 

 those not conversant with the fixed relations of osteological and dental characters, that 

 the three corresponding parts of three Pterodactyles, for the first time discovered, 

 should be appropriated to three distinct species, I have no other alternative, in 

 obedience to the indications of Nature, than to adopt such determination. 



The portions of the skull of the Pterodactylus compressirostris, like those of the 

 Pt. Cuvieri and Pt. giganteus, were discovered in the Chalk-pit at Burham, Kent, and 

 are in the Collection of James Scott Bowerbank, Esq., F.R.S., to whose skill is due 

 the exposure of the palatal surface and the left side of the portion of the jaw, figured 

 in T. XXVIII, figs. 8 and 10. 



Long Bones of Pterodactylus Cuvieri. Tab. XXX, figs. 1, 2, and 3. 



The bone which, from its size, and from the character of its external surface may 

 be, with most probability, referred to the largest of the above-defined species of 

 Cretaceous Pterodactyles, is that which forms the subject of figures 1, 2, and 3, 

 T. XXX. It was discovered in the Chalk-pit, at Burham, Kent, and is now in the 

 Collection of J. Toulmin Smith, Esq., of Highgate. 



The length of the bone in proportion to its thickness is too great to be compatible 

 with its being the humerus ; and indicates it to be either one of the antibrachial bones ; 

 or, more probably, from its similarity in shape to the long bones of most frequent 

 occurrence in smaller species, the first or the second phalanx of the elongated wing-finger. 



One end of the bone is nearly entire, the other end is wanting, the total length of 

 the specimen being 14^ inches. The longest diameter of the preserved extremity is 

 2 inches 3 lines, whence the shaft decreases to a diameter, in the same direction, of 

 1 inch, and then more gradually expands to a diameter of 1 inch 3 lines at the 

 fractured end. The shaft soon assumes a triedral figure, with the angles rounded off, 

 and the breadth of the narrowest side is shown in fig. 3. The contour of the best 



