18 



we take into consideration the comparative length of each bone with 

 regard to its total extension, as exhibited in the table of the dimen- 

 sions of P. longirostris. In the case of the great specimens of radius 

 we may arrive at their length in many cases, although the bone may 

 be imperfect at even both terminations. Thus the diameter of the 

 smallest portion of the bone formerly in the possession of the Earl of 

 Enniskillen and figured by Prof. Owen, is "81 inch at the smallest 

 portion of the shaft : this bone therefore, on the scale of 13^ diame- 

 ters to its length, should be I0'93 inches in length. The measure- 

 ment of the smallest portion of the bone belonging to Mrs. Smith 

 (Geol. Journ. vol. iv. pi. 2. fig. 1 «) is "77 inch : we may therefore, by 

 the same rule, conclude that its length was 10'39 inches when per- 

 fect. The length of the imperfect ulna beside it is 9*25 inches in the 

 specimen. The diameter of the smallest portion of the bone (Geol. 

 Journ. vol. ii. pi. 1 . fig. 6) is "45 inch, which, in the proportion of 13|- 

 diameters to its length, will give 6 "07 inches for its length. The 

 width of the corresponding bone in the possession of Mr. Charles of 

 Maidstone is \'2b inch at the smallest diameter: by the same rule, 

 therefore, the approximate length should be 16"87. The remains of 

 the bone alongside of it is, although imperfect at both ends, actually 

 I2'25 inches in length. 



Upon these grounds therefore, in every case derived as much as 

 possible from direct measurements from the skeletons of the respective 

 species, I have given the following table of the dimensions of a series 

 of species of Pterodactyls, the most interesting either from the state 

 of perfection in M'hich their remains have been found, or from the 

 gigantic proportions which they present ; and thus have endeavoured 

 to realize to the mind an idea, as nearly as possible correct, of the di- 

 mensions of the animals when alive. 



Table of the relative proportions of known species oi Pterodactxjliis, 

 with the length of each of the wing-bones and half of the width of 

 the body. 



In the above table I have presumed that the largest bones should 

 be associated with the snout described as the type of P. Cuvieri, but 

 the truth of this assignment of the bones belonging to Mr. Charles 



