308 Trof. a. G. Seeley — On Vogfs Vieio of the ArchcBopteryx. 



and the similar skeleton at Stuttgart, are botli examples of Ptero- 

 dactyles with long hind-legs. Certain other Ornithosaurs have 

 the hind-limbs relatively small, but it is open to consideration 

 ■whether flight may not have attained its development in those 

 animals after the vertical position of body had been acquired. It 

 might be as well also to recognize that there is no published 

 evidence of fundamental difference in the hand between Pterodac- 

 tyles and Birds such as Prof. Vogt represents. Omitting for the 

 moment the evidence that Ornitlioclieirus from the Cambridge Green- 

 sand had three digits, saying nothing about the embryological 

 evidence as to primitive indications of four digits in the manus of 

 the bird, it may be laid down once for all that the restorations 

 which give the Pterodactyles five digits in the hand belong to a 

 prehistoric period. Oken, Wagler, and Goldfuss, it is true, thought 

 there were five digits, and the restoration of the latter writer has 

 been frequently reproduced, but no specimen could ever be found in 

 support of such an interpretation, and it has long since been aban- 

 doned by every one pretending to draw his knowledge from speci- 

 mens. It is thei'efore astonishing to see a figure given of the fore- 

 limb of BliampTiorhynchus in which there are four clawed digits. One 

 cannot but ask where the specimen is to be seen which shows the 

 structure of fore-limb depicted in Prof. Vogt's figure. If the figure 

 is faithfully copied from the photograph to which Prof. Vogt refers 

 as of Rhamphorhynchus gemmingii, it certainly belongs to a new and 

 undescribed type of Ornithosaur. The Arch^opteryx is in no respect 

 a modified Pterodactyle ; but it has enough in common with the 

 Pterodactyles to make that group in some respects better illustrative 

 of its skeletal structures than Dinosaurs. 



Finally the Professor considers the influence of the feathers in 

 changing the skeleton of a reptile into that of a bird, suggesting that 

 the ancestors of the bird were scaly lizards. Briefly it is the author's 

 view that modification of organization proceeds from " the skin to the 

 skeleton," and that the latter may be wholly unaffected when the 

 former has already reached the development of feathers. Now 

 this view renders the position taken up by Vogt perfectly logical, 

 but the view itself is, as a general principle, not so obviously 

 logical, because it is shown by the existence of other flying animals 

 that flight itself does not necessarily change an animal's grade of 

 organization. If the Arch(eopteryx were the modified reptile that 

 it is assumed to be, the development of feathers might tend towards 

 an avian modification of the manus, but not inevitably, since the 

 clawed condition persists in one digit in the bat, as well as in 

 several in the Ornithosauria. No doubt the development of feathers 

 was correlated with an important modifj'ing influence on the ex- 

 tremities of the skeleton in the bird ; but the feathers themselves 

 must be presumed to have been slowly evolved, and from their first 

 existence must have tended to modify muscles in ways that would 

 have contributed to change the skeleton, so that I cannot conceive 

 of the existence of well-developed plumage without a correlative 

 modification of the skeleton. 



