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BARON NOPCSA ON THE 



[Feb. 19, 



equally strong metatarsals which all approximately attain the same 

 length, while, in harmony with the lack of a tail, of the 5th toe 

 only a rudiment (text-fig. 76) now remains. Among Chu-optera we 

 find that in the tailless forms, notably Pteropus, quite similarly 

 the OS calcar of the hind leg is less developed than in the long- 

 tailed species. 



Text-fia-. 76. 



Hind limb of Fterodactylws. 

 (The rudiment of the 5th toe is unfortunately not shown in this drawing.) 



On account of the anterior prolongation of the ilium in 

 Pterosaurs, and on account of the great number of vertebrpe l^nited 

 in the sacrum, it has been fi-equently assumed that the Pterosaurs 

 enjoyed a bipedal locomotion. Both these arguments, however, 

 fail to convince me, and this principally on account of Nyctosaimms, 

 which, although certainly not a bipedal genus, has a still greater 

 number of sacral vertebrse, and because in Pteropus there is like- 

 wise a pseudosacrum present. Another argument that can be 

 brought forward as annulling the hypothesis just mentioned 

 consists in tire fact that the Pterosaur pelvis, though showing 

 considerable length, has an ilium of an exceedingly low and 

 narrow Bat-like outline. 



A Ptei"0saur of whose crawling habits we oan be quite sui-e is, 

 as just mentioned, the Upper Cretaceous Nyctodactylus, for, as 

 Williston pointed out, the acetabulum is placed far back, nearly over 

 the edge of the sacrum, so that it was impossible for the knees in this 

 animal to meet in the middle, and at times the knees may even 

 have been turned more or less backward. When the femora 

 were rotated outward and abducted, the tibise might have been 

 brought parallel with each other. Exactly similar conditions are 



