Fes., 1912. MamMats oF ILLINo1s anp WISCONSIN — Cory. 23 
inches in length and slightly more in breadth, and extending from it 
is what is known as the vermiform appendix, a narrow worm-like 
tube which is, so far as known, found only in Man, the higher Apes 
and the Wombat. 
The Liver — This organ is situated on the right side of the abdominal 
cavity, and is usually divided into a right and left half, being again 
subdivided by deep clefts into lobes 
in different mammals. As a rule, 
these divisions are more numerous in 
carnivorous animals than in vege- 
table feeders. The gall bladder is 
present in some species and absent 
in others. 
Urinary Organs — The kidneys in most 
mammals are compact, oval-shaped 
i: Eley of bin erty Sta of Suites organs, having a depression at the 
of a ma d a 
Panay oe border where the ducts enter; but in 
a few cases they are lobate, as in the 
Whales, Seals, Bears, some of the Ungulates, and a few others. 
They are situated in the back part of the abdominal cavity behind 
the peritoneum and opposite the upper lumbar vertebra, and as a 
rule one of them lies in a more advanced position than the other. 
The ureters connect the kidneys with the urinary bladder and open 
directly into it in the higher Mammalia, but lower down into the 
urino-genital passage in the lower members of the class. 
Reproductive Organs — Lengthy discussion of this group of organs is 
unnecessary here, and will be confined to a few general statements 
concerning them. 
In all mammals a penis is present and almost always completely 
developedin the male. Inthe Ferz, Glires, Insectivora, Chiroptera, 
and all except a few of the higher Primates, an os penis is present, 
but is lacking in the other orders. The testes of the male in the 
majority of cases pass out of the abdominal cavity either periodically 
(as in Insectivora, Chiroptera and Glires), or permanently, as in 
most other mammals, and in the latter case, are suspended ina 
pouch or scrotum. In the Marsupials the testes are suspended in 
front of the penis. 
In the Whales, Seals, Elephants, Monotremes, most of the 
Edentates, and several others, they retain their internal position 
throughout life. 
In all mammals, except the Monotremes and most of the Mar- 
supials, a placenta is formed by a union of the alantois with the 
