388 Zoological Society. 



the upper jaw, of seven inches in extent, without any trace of the 

 nasal or any other natural perforation of its upper or lateral parietes. 

 From the number of teeth contained in this part, the Pt. Cuvieri pre- 

 sents a much closer resemblance to the Ft. longirostris than to the 

 Pt. crassirostris ; and if the entire skull were restored according to 

 the proportions of the Pt. longirostris, it would be twenty-eight 

 inches in length. 



But nature seems never to retain the same proportions in species 

 that differ materially in bulk. The great Diprotodon, with the den- 

 tal and cranial characters of a Kangaroo, does not retain the same 

 length of hinder hmbs as its hving homologue ; the laws of gravity 

 forbid the saltatory mode of locomotion to a Herbivore of the bulk of 

 a Rhinoceros ; and accordingly, whilst the hind-legs are shortened 

 the fore-limbs are lengthened, and both are made more robust in the 

 Diprotodon than in the Kangaroo. The change of proportions of 

 the limbs of the Sloths is equally striking in those extinct species 

 which were too bulky to climb, e. g. the Megatherium and Mylodon. 

 We may therefore infer, with a high degree of probability, when a 

 longirostral Pterodactyle much surpassed in bulk the species so called 

 • par excellence/ that the same proportions were not maintained in 

 the length of the jaws ; and that the species to which the fine frag- 

 ment belonged, far as it has exceeded our previous ideas of the bulk 

 of a flying reptile, did not sustain and carry through the air a head of 

 two feet four inches in length, or nearly double the size of that of the 

 Pelican. 



Although the fractured hinder part of the jaw of the Pt. Cuvieri 

 shows no trace of the commencement of the wide nasal aperture, there 

 is a plain indication that the jaws were less prolonged than in the Pt. 

 longirostris, in the more rapid increase of the vertical breadth of the 

 jaw. Opposite the ninth tooth, e. g., the depth of the jaw equals two- 

 fifths of the length in advance of that tooth, whilst in the Pt. longi- 

 rostris it is only two-sevenths. The contour of the upper border of 

 the jaw in the Pt. Cuvieri differs from that in both the Pt. longi- 

 rostris, Pt. crassirostris, and Pt. Gemmingi, in sinking more sud- 

 denly opposite the ninth, eighth and seventh teeth, than it does along 

 the more advanced part of the jaw ; a character which, while it affords 

 a good specific distinction from any of those species, indicates the 

 hinder parts of the head that are wanting in the present specimen to 

 have been shorter and deeper than in the Pt. longirostris. 



The first pair of alveoli almost meet at the anterior extremity of 

 the jaw, and their outlet is directed obUquely forwards and down- 

 wards ; the obtuse end of the premaxillary above these alveoli is about 

 two lines across. The palate quickly expands to a width of three 

 lines between the second alveoli, then to a width of four lines between 

 the fourth alveoli, and more gradually, after the ninth alveoli, to a 

 width of six lines between the eleventh alveoli : here the palate ap- 

 pears to have been slightly crushed ; but in the rest of its extent it 

 presents its natural form, being traversed longitudinally by a mode- 

 rate median ridge, on each side of which it is slightly concave trans- 



