B. III.] THE HISTOBY OF ANIMALS. 49 



which are said to have a crumbling roe had hut two ova, for 

 it is not one ovum but many, and therefore it may be resolved 

 into many. 



12. In the uterus of birds the vagina is below, fleshy and 

 tough, but the part near the diaphragm membranaceous and 

 rery thin, so that the eggs appear to be outside the uterus. 

 In large birds the membrane is more conspicuous, and if 

 inflated through the vagina, it swells and enlarges at places ; 

 in small birds these parts are not conspicuous. The uterus 

 of oviparous quadrupeds, as the tortoise, lizard, frog, and 

 such like, is of the same nature, for the vagina below is one 

 and fleshy, but the division and the ova are higher up and 

 near the diaphragm. 



13. In those apodal creatures which are outwardly vivi- 

 parous and inwardly oviparous, as the sharks and selachea 

 [The selachea are apodal, furnished with gills, and vivi- 

 parous] the uterus is divided, and as in birds, it com- 

 mences below and extends towards the diaphragm. The 

 ova are situated between the division, and above near the 

 diaphragm ; and the animal is produced from the ovum after 

 this has descended into the open space. 



14. The difference between the uteri of these fish and 

 others may be studied more accurately in drawings of dis- 

 sections. Serpents also differ much both among themselves 

 and from other animals, for all serpents except the viper are 

 oviparous ; this one is viviparous, though at first internally 

 oviparous, wherefore, in many rsspects, its uterus resembles 

 that of the cartilaginous fishes. The uterus of the serpent 

 is long, like the body, and descends downwards, beginning 

 from one duct and continuing on either side of the spine as 

 far as the diaphragm, as if each were a passage, in which the 

 ova are placed in order ; these ova are not extruded singly, 

 but connected together like a chain. 



15. In all animals that are either internally or externally 

 viviparous, the uterus is situated above the abdomen ; in all 

 oviparous creatures it is placed below, near the loins. Those 

 that are externally viviparous, but internally oviparous, par- 

 take of both characters, for the lower part in which the ova 

 are situated is near the loins, the other part whence the ova 

 are extruded above the intestines. And there is also this 

 difference in the uteri of animals ; those which have horns 







