11. 9- 41 



part after a meal, nor, in females, any interference with the growth 

 of the embryo, which is lodged here.^ 



Now the bones of viviparous animals, of such that is as are not 

 merely externally but also internally viviparous,* vary but very 

 little from each other in point of strength, which in all of them is 

 considerable. For the vivipara in their bodily proportions are far 

 above other animals, and many of them occasionally grow to an 

 enormous size, as is the case in Libya and in hot and dry countries 

 generally. But the greater the bulk of an animal, the stronger, the 

 bigger, and the harder, are the supports which it requires; and 

 comparing the big animals with each other, this requirement will 

 be most marked in those that live a life of rapine. Thus it is that 

 the bones of males are harder than those of females ; and the 

 bones of flesh-eaters, that get their food by fighting, are harder 

 than those of herbivora. Of this the Lion is an example ; for so 

 hard are its bones, that, when struck, they give off sparks, as 

 though they were flints. It may be mentioned also that the 

 Dolphin, inasmuch as it is viviparous, is provided with bones and 

 not merely with fish-spines.^ 



In those sanguineous animals, on the other hand, that are 

 oviparous, the bones present successive slight variations of charac- 

 ter. Thus in Birds there are bones, but these are not so strong 

 as the bones of the Vivipara.^ Then come the Oviparous fishes, 

 where there is no bone, but merely fish-spine. In the Serpents 

 too the bones have the character of fish-spine, excepting in the 

 very large species,''' where the solid foundation of the body requires 

 to be stronger, in order that the animal itself may be strong, the 

 same reason prevailing as in the case of the Vivipara, Lastly in 

 the Selachia, as they are called, the fish-spines are replaced by 

 cartilage. For it is necessary that the movements of these animals 

 shall be of an undulating character ; and this again requires the 

 solid framework of the body to be pliable, and not rigid in its 

 motions. Moreover in these Selachia ^ nature has used all the 

 earthy matter on the skin ; and she is unable to distribute to 

 many different parts one and the same superfluity of material.^ 

 Even in viviparous animals many of the bones are cartilaginous. 

 This happens in those parts where it is to the advantage of the 

 surrounding flesh that its solid base shall be soft and mucilaginous. 

 Such, for instance, is the case with the ears and nostrils ; for in 

 projecting parts, such as these, rigid substances would soon get 

 655 a. 



