MORPHOLOGY 473 



some other Australian marsupials, — should all be constructed 

 on the same extraordinary type, namely with the bones of 

 the second and third digits extremely slender and enveloped 

 within the same skin, so that they appear like a single toe 

 furnished with two claws. Notwithstanding this s'milarity 

 of pattern, it is obvious that the hind feet of these several 

 animals are used for as widely different purposes as it is pos- 

 sible to conceive. The case is rendered all the more striking 

 by the American opossums, which follow nearly the same 

 habits of life as some of their Australian relatives, having 

 feet constructed on the ordinary plan. Professor Flower, 

 from whom these statements are taken, remarks in conclu- 

 sion : '"We may call this conformity to type, without getting 

 much nearer to an explanation of the phenomenon ;" and he 

 then adds, "but is it not powerfully suggestive of true rela- 

 tionship, of inheritance from a common ancestor?" 



Geoffroy St. Hilaire has strongly insisted on the high im- 

 portance of relative position or connexion in homologous 

 parts; they may differ to almost any extent in form and size, 

 and yet remain connected together in the same invariable 

 order. We never find, for instance, the bones of the arm 

 and fore-arm, or of the thigh and leg, transposed. Hence 

 the same names can be given to the homologous bones in 

 widely different animals. We see the same great law in the 

 construction of the mouths of insects: what can be more dif- 

 ferent than the immensely long spiral proboscis of a sphinx- 

 moth, the curious folded one of a bee or btig, and the great 

 jaws of a beetle? — yet all these organs, serving for such 

 widely different purposes, are formed by infinitely numerous 

 modifications of an upper lip, mandibles, and two pairs of 

 maxilla;. The same law governs the construction of the 

 mouths and limbs of crustaceans. So it is with the flowers 

 of plants. 



Nothing can be more hopeless than to attempt to explain 

 this similarity of pattern in members of the same class, by 

 utility or by the doctrine of final causes. The hopelessness 

 of the attempt has been expressly admitted by Owen in his 

 most interesting work on the 'Nature of Limbs.' On the 

 ordinary view of the independent creation of each being, we 

 can only say that so it is; — that it has pleased the Creator 



