77 



from the following extract from a letter of that gentleman quotcd ia 

 Kirby's Bridgewater Treatise, vol. ii. p. 432 : — " Dissections of most 

 of the genera of Marsupians have tended to confirm in my mind the 

 propriety of establishing them as a distinct and parallel group, be- 

 ginning with the Monotremes, which I believe to lead from Reptiles, 

 not Birds." Again, in his paper * On the Young of the Ornitho- 

 rhynchus paradams,' Zool. Trans. vol. i. p. 221, he very distinctly 

 States the \veight of evidence to be in favour of the relation of the 

 Monotremates to the Reptiles rather than Birds ; so that in all pro- 

 bability he has altered his views on this subject since 1830. 



The evidence produced above is conclusive for my purpose, and 

 precludes the necessity of discussing the analogies of the Monotre- 

 mata. But as Prof. Owen has alluded to the beak of the Ornitho- 

 rhynchus as that " of a bird," it may not be irrelevant to show in how 

 many important particulars the two structures difFer. " This struc- 

 ture," says Sir Everard Home, speaking of the organ in ąuestion, 

 " differs materially from the bill of a Duck, and indeed from the bill 

 of all birds, since in them the cavities of the nostrils do not extend 

 beyond the root of the bill ; and in their lower portions, Tybich cor- 

 respond to the under jaw of ąuadrupeds, the edges are hard, to 

 answer the purpose of teeth, and the middle space is hollow, to re- 

 ceive the tongue" (Home on Head of Ornithorhynchus, Phil. Trans. 

 1800). Wlien to this diversity of structure we add the difFerence 

 of use, we shall see that hovvever strong may be the resemblance at 

 first sight, it is perhaps more imaginary than real. From the de- 

 scription above-quoted,we learn that the beak of the Ornithorhynchus 

 is incapable, from the general flexibility of its structure, of taking 

 firm hold of any object ; but that the marginai lips being brought 

 together, the prey is sucked into the mouth. 



Perhaps too the similarity of the spines of the Echidna to the 

 quills of a bird is not very close. 



7. The pelvis of some Edentata certainly resembles that of Birds 

 in a remarkable degree. 



I have thus endeavoured to show that many of the structures in 

 the Edentata, adduced by Prof. Owen as oiFering relations to Birds, 

 are eąually so to Reptiles ; whilst those that lead us to the former 

 class are not of equal number or importance to those that conduot us 

 to the latter. 



I am fully aware that the scope and conduct of my investigations 

 have been defective ; but so far as they extend they appear to me to 

 prove simply this, viz. that tlie Edentata are allied to the Reptiles, 

 and that more nearly than to Birds. 



It would have been absurd to expect any other result from this 

 investigation than such as the present : a group is never related to 

 one other group only : " The true affinities of organic structures 

 branch out irregularly in all directions." 



I caimot conclude without observing, that it is highly remarkable 

 and interesting that affinities should be found to prevail amongst 



