1907.] 



ORIGIN OF FLIGHT. 



225 



but the 5th is somewhat thicker and also much shorter. The 

 elongate phalanges of the 5th toe further prove clearly that no 

 cursorial adaptation modified the form of these bones. Yery 

 much the same type of foot is visible in the equally long-tailed 

 Campylognathus \ and when we turn to the Rhamjjhorhyndms of 

 the Solenhofen Slate (text-fig. 75), we find not only no cursorial 

 modification of the four-toed slender foot but quite decided degene- 

 ration. However, according to Zittel, the number of phalanges in 

 the 5th toe is perhaps somewhat greater than in the drawings 

 given for Dimorphodon or Campylognathus. Since the spur-like 

 clawless 5th digit of the foot is very strongly developed in Dimor- 

 phodon, there is, as Owen observed, good reason to believe that a 



Text-fig. 75. 



Hind limbs of Tlhamfliorliynclms. 



uropatagiuna was not only present bub even very well developed ;. 

 whereas we know that in Rhamphorhynchus, in accordance with 

 the less developed 5th toe, no uropatagium extended to this part of 

 the body. The resemblance of the Rhamphorhynchus sternum 

 to that of the Bat (Taphozous^ likewise has to be noticed. 



That in the Liassic Dimorphodon the wing-finger is relatively 

 shorter than in the Tithonian Rhamphorhynchus is a fact so 

 obvious as scarcely to demand attention. The short-tailed 

 Pterosaiiria of the genus Pterodactylus, with comparatively short 

 wing-bones, resemble Campylognathus in having four feeble and 



Proc. Zool. Soc— 1907, No. XV. 15 



