OF OEGANIC SPECIES. 23 



here done for the Horse — that is, to mark off and dis- 

 tinguish the particular district or region to which each 

 belonged ; and supposing we tabulated all these results, 

 that would be called the Geographical Distribution of 

 animals, while a corresponding study of plants would 

 yield as a result the Geographical Distribution of plants. 



I pass on from that now, as I merely wished to 

 explain to you what I meant by the use of the term 

 " Geographical Distribution." As 1 said, there is another 

 aspect, and a much more important one, and that is, 

 the relations of the various animals to one another. 

 The Horse is a very well defined matter-of-fact sort of 

 animal, and we are all pretty familiar with its structure. 

 I dare say it may have struck you, that it resembles 

 very much no other member of the animal kingdom, 

 except perhaps the Zebra or the Ass. But let me ask 

 you to look along these diagrams. Here is the skeleton 

 of the Horse, and here the skeleton of the Dog. You 

 will notice that we have in the Horse a skull, a back- 

 bone and ribs, shoulder-blades and haunch-bones. In 

 the fore-limb, one upper arm-bone, two fore arm-bones, 

 wrist-bones (wrongly called knee), and middle hand- 

 bones, ending in the three bones of a finger, the last 

 of which is sheathed in the horny hoof of the fore-foot : 

 in the hind-limb, one thigh-bone, two leg-bones, ankle- 

 bones, and middle foot-bones, ending in the three bones 

 of a toe, the last of which is encased in the hoof of the 

 hind-foot. Now turn to the Dog's skeleton. We find 

 identically the same bones, but more of them, there 

 being more toes in each foot, and hence more toe-bones. 



Well, that is a very curious thing ! The fact is 

 that the Dog and the Horse — when one gets a look at 

 them without the outward impediments of the skin — 



