XVI] IN THE SKELETON OF QUADRUPEDS 1003 



It will be observed that in all these animals the load upon the 

 fore-feet preponderates considerably over that upon the hind, the 

 preponderance being rather greater in the elephant than in the horse, 

 and markedly greater in the camel and the llama than in the other 

 two. But while these weights are helpful and suggestive, it is 

 obvious that they do not go nearly far enough to give us a full 

 insight into the constructional diagram to which the animals are 

 conformed. For such a purpose we should require to weigh the 

 total load, not in two portions but in many; and we should also 

 have to take close account of the general form of the animal, of 

 the relation between that form and the distribution of the load, 

 and of the actual directions of each bone and ligament by which 

 the forces of compression and tension >were transmitted. All this 

 lies beyond us for the present; but nevertheless we may consider. 



Tail 



Head 



Fig. 480. Stress- diagram of Titanotheriuni. 



very briefly, the principal cases involved in our enquiry, of which 

 the above animals form a partial and preliminary illustration. 



(1) Wherever we have a heavily loaded anterior cantilever arm, 

 that is to say whenever the head and neck represent a considerable 

 fraction of the whole weight of the body, we tend to have large 

 bending-moments over the fore-legs, and correspondingly high spines 

 over the vertebrae of the withers. This is the case in the great 

 majority of four-footed terrestrial animals, the chief exceptions 

 being found in animals with comparatively small heads but large 

 and heavy tails, such as the anteaters or the Dinosaurian reptiles, 

 and also (very naturally) in animals such as the crocodile, where 

 the " bridge " can scarcely be said to be developed, for the long heavy 

 body sags down to rest upon the ground. The case is sufficiently 

 exemplified by the horse, and still more notably by the stag, the ox, 

 or the pig. It is illustrated in the skeleton of a bison (Fig. 468), or 



