74 THE DISEASES AND DISOEDERS OF THE OX. 



ungulates have diffuse and some have cotyledonous placenta. 

 The giraffe has a transitional form of placenta, namely — patches 

 with occasionally a few villi. Hence in the tragulus and camel 

 the placentation is diffuse, in the giraffe it is of an intermediate 

 kind, and in other ruminants it is cotyledonous. In having a 

 diffuse placentation the tragulus and the camel are like the mare 

 and the sow. All ruminants are non-deciduate, and in this 

 point they agree with all cetacea. 



Embryology. — Ox. — At twenty-eight days the embryo has a 

 length of I" inch, and corresponds in its development to the 

 sheep's embryo of twenty-five days. 



Sheep. — The embryo of the sheep at eighteen days has a 

 length of ^ inch. At twenty-three days signs of the feet appear. 

 After twenty-five days it has a length of | inch, and indications 

 of the eyes, ears, and tail are present. The intestine exists as a 

 tube connected with the umbilical vesicle. The Wolffian body 

 is well developed. 



The giraffe is the only animal which is born with horns. The 

 embryonic period of the giraffe is 444 days. That of the sheep 

 is only nine months. 



THE CIRCULATORY SYSTEM. 



The blood-corpuscles of ruminants differ from those of other 

 animals in being rather small. In camels the corpuscles are 

 elliptic, and some are round. In the llama the round cells are 

 more numerous, but not so numerous as the elliptic cells. In 

 the giraffe they are about ^-g-J-o Jiich in diameter, in tragulus 

 —^■wwo iwch, and in man about -^\-qq inch. The heart is conical 

 in ruminants. There are bony developments in the heart of 

 the ox, in that of the red deer, and that of the giraffe, at the 

 point of union of each auricle with the corresponding ventricle. 

 They constitute the most prominent characteristic feature of 

 the heart in ruminants. They appear in adult life, are two in 

 number, and lie between the auriculo-ventricular rings and the 

 common aorta on the left and the pulmonary artery on the right 

 side. The mitral valves are not so separate as the tricuspid. 



The moderator band, a muscular development, occurs in the 

 right ventricle in ruminants as well as in some other animals, e.g. 

 the ostrich. There are retia mirabiha in the cranium, and large 

 sinuses run round the base of the sella turcica. Creatures like 



