wr 
Monograph on Dimorphodon. 147 
vital organs which determine the systematic place of the ani- 
mal. ‘This comparison can be made with birds, and with the 
living orders of reptiles, because the skeleton in them is the 
exponent of definite and known kinds of organization in the 
lungs, and heart, and brain, and reproductive organs. lfit were 
not, comparison could give little or no clue to affinity. Bu 
in Enaliosauria, Dinosauria, and Dic odontia not one of these 
organs is known ; and I cannot but consider the packing of these 
groups into the Reptilia, in the absence of such knowledge or 
even of osteological coordination *, entirely subversive of scien- 
tific investigation. If such comparisons are made, t ea 
ties must be spoken of as Dinosaurian or Iehthyosaurian for 
instance, but never as Reptilian; otherwise the word Reptile 
becomes meaningless, and we substitute personal fancies about 
an animal's affinities for knowledge; this would be the result 
of accepting Prof. Owen's views. Prof. Owen, however, has 
abstained from making any other comparisons of this kind, 
except those already noticed. 
s The length and flexibility of the neck is correlated with 
the covering necessitated by the high temperature of the bird. 
The cold-blooded flying reptiles have a comparatively short 
and rigid neck," &c. (p. 67). Such a doctrine is misleading, 
since in many Plesiosaurs the neck is even longer than in 
birds, and often not less flexible; yet there is no ground for 
affirming that they were covered with feathers or had hot 
blood ; while in mammals the neck is usually at least as short 
as in Pterosaurs. The argument about the covering is con- 
* This I have attempted in a MS. catalogue of the Woodwardian 
Museum. 
: 10* 
