LEPUS 149 



The veins from the hind legs (iliac and femoral veins) run 

 into the inferior vena cava, which also receives the genital vein 

 from the gonads, the renal veins from the kidneys and the 

 hepatic veins from the liver, and runs into the right auricle. 

 Blood from the stomach and intestine is carried to the liver 

 by the hepatic portal vein : there is no renal portal vein. The 

 blood of the mammals differs from that of all other animals 

 in that in the adult, the red blood-corpuscles have no nuclei. 

 Instead of being biconvex, the red corpuscles here are bicon- 

 cave. The source of supply of new blood-corpuscles in late 

 embryonic and in adult life is in the red marrow which is 

 situated in the central cavity of a number of bones. In 

 addition, lymphocytes are produced in the lymph- glands, 

 which also serve as blood-filters. It is possible that blood- 

 corpuscles may also be formed in the spleen. 



Like birds, mammals are warm-blooded, or homothermous. 



Urino-genital System. — The kidneys are asymmetrically 

 placed. They are metanephric structures, connected by the 

 ureters with the urinary bladder. 



In the female the Mullerian ducts persist while the Wolffian 

 ducts disappear together with the mesonephros (traces of the 

 latter may persist as the epoophoron and paroophoron). The 

 ovaries are close to the anterior end of the Mullerian ducts or 

 oviducts, which open into the peritoneal cavity by the Fallopian 

 tubes. The base of each oviduct is enlarged and specialised 

 to form the uterus, in which the young embryos develop, for 

 mammals are viviparous. The two uteri are close together, 

 and they open into the single median vagina. The bladder is 

 just ventral to the vagina and connects with it to form the 

 vestibule which communicates with the exterior by the vulva. 



The vestibule is dorsal to the pubic symphysis, and ventral 

 to the anus, with which it has no connexion. There is therefore 

 no cloaca. 



In the male, the Mullerian ducts disappear except for the 

 uterus masculinus, which lies dorsal to the bladder. The 

 testes are connected with the epididymis, representing the 

 mesonephros of their own side. From the epididymis the vas 

 deferens or Wolffian duct leads to the base of the bladder on its 



