FOUND LINKS. 14 r 



The arrangements of the internal organs in many 

 respects present the closest likeness to the anatomy 

 of birds and reptiles, and this is particularly the case 

 with those structures in the quadrupeds which repre- 

 sent the egg-producing organs of the bird and reptile. 

 Even the typical mammalian characters are but feebly 

 represented in these lowest quadrupeds. We kno\\r 

 that the young, although born alive, as in quadruped' 

 life at large, are provided with a horny knob on the 

 upper jaw, such as is seen in the young bird ; and no- 

 teats exist in the milk-glands of these forms, a feature 

 represented in all other members of their class. 



Summing up the inferences to be drawn from our 

 brief study of the lowest quadrupeds, we may legiti- 

 mately hold, firstly, that they are of essentially lower- 

 structure than other mammals ; secondly, that all the 

 points in which they evince this inferiority ally them, 

 at the same time, to birds and reptiles ; and thirdly, 

 that the only feasible explanation of the differences 

 in question is that which regards them as arising 

 from the nearer relationship the result of heredity 

 and descent which these lowest quadrupeds present 

 to birds and reptiles. 



In a concluding paper, I shall strive to show the- 

 nature of the links which unite the Vertebrate animals, 

 to their lower and Invertebrate neighbours. 



