550 



BRITISH FOSSIL REPTILES. 



equals the largest known vertebra of an unquestionable Pterodactyle (corap. Pter., PL S, 

 figs. 7, 11, and Pter., PI. 12, figs. 1 and '2). But tiiese pterosaurian vertebrae are from 

 the region of the neck, and served to sustain a head which, from the proportions of that 

 in Dimorphodon mucronyx {Pter., PL 17), and most probably also in CriorhyndiuH >iiiuu>i 

 {Pter., PL 11, figs. 1 — 3) and Coloborhi/nchtis dmirostris {Pter., PL 19, figs. 1 — 4), was 

 considerably larger in relation to the trunk and wings than in the largest examples of 

 ])irds capable of flight. We may with I'eason, therefore, assume that the total magnitude 

 or weight capable of being raised and sustained in air was not greater in the cold-blooded, 

 naked, volant reptile than in the warm-blooded, feathered bird. The instruments of 

 flight were, however, relatively longer in Pterosauria. In illustration of this pi-oposition 

 1 subjoin admeasurements of the chief parts of the skeleton in the best-restored specimen 

 of a flying dragon, viz. that of Di)norphodon macronyx. 



„ fourth or wing-finger 

 ,, bones of a wing, from head of humerus 

 to end of wing-finger 

 Breadth of trunk between articular ends of right 



and left scapulae 

 Span of outstretched wings, including breadth of 

 trunk 



Now, the largest neck-vertebra of Criorhynclms simus {Pter., PL 12, fig. 1) is rather 

 more than two such vertebra? in Bimorpliodon macrony.v. Other things being equal, 

 therefore, we may assign to Criorhynchus simus a span of outstretched wing of nine or 

 ten feet. 



Birds, like the cassowary, ostrich, and moa, which have attained a bulk superior to 

 that of the albatross, obey the law of gravitation, and lose the faculty of soaring above 

 the surface of the earth. We may with reason, therefore, conclude that we have in 

 Criorhynclms simus and Coloborhynchus davirostris the extremes of magnitude in the 

 volant Reptilia. 



