472 Recent freshioater Molliisca, 



ern Felis domestica; and such was the general opinion, until 

 the discovery, by Dr. Rijppell, of the genuine analogue of the 

 embalmed species, in the Felis maniculata of Noubia. I be- 

 lieve Professor Bell to be correct in deciding that Felis domes- 

 tica can neither be referred to this species, nor to the Felis 

 catus found wild in the forests of Europe.* Again, great 

 stress has been laid upon the contrasts presented by the so 

 called varieties of the domestic dog ; but the hint given by 

 Pallas, that they are merely prolific hybrids,-)- accounts for the 

 variations in a much more satisfactory manner than to suppose 

 them identical with some single primary form. Col. Hamilton 

 Smith, in his valuable treatise on the Canida3, J has developed 

 these views in a masterly manner, and, at the same time, has 

 reduced the family to such perfect order, that I do not hesi- 

 tate to adopt his views. *§> The lamarckian hypothesis of 

 appetency, as he left it, seems clearly untenable, but, in a 

 modified form, affords room for further discussion. Thus it 

 appears impossible that a bird, with detached toes, should 

 ever acquire webbed feet by mere dint of swimming or desire 

 to swim ; but, as all animals are formed with a greater or less 

 approximation to certain models, why may not the germ which 

 would result in a swimming organ (as that to which the water 

 dogs owe their partially webbed feet) be present in a terres- 

 trial animal, just as the foetal brain is successively that of a 

 fish, reptile, and bird, before it is that of a perfect mammal ? 

 or as the mammary glands have been known to increase in 

 number, and to occur by deviation, in the inguinal region of 

 the human subject ? 



* British Quadrupeds, p. 185. 



+ Caldwell's Unity of the Human Race. 



t Nat. Libr. See, also. Horses, p, 70, where he remarks, '•' It seems, therefore, 

 more consonant with the distribution of several genera of animals on the earth's 

 surface, to believe that osculating forms existed ab initia distinct, circumstanced to 

 accomplish certain ends, such as the service of man, and therefore framed so as to 

 render them fusible into one species." The same view had been previously taken by 

 Mr. Eyton, a British ornithologist, Mag. Nat. Hist. (N. S.) i. 359. 



§ If these prevail among zoologists, it will be necessary for the pseudo-lamarckians 

 to remodel their arguments to some extent, as they will be reduced to such " facts " 

 as are given in the next note but one. 



II In the eyeless fish and crustacean of the Kentucky cave, the germs of visual 

 organs must exist, and only require light to cause the ej'es themselves to appear ii> 



