URINARY SYSTEM _.. 69 
arise from the upper part of the nasal passages, and lie immediately 
under the skin of the face. These appear analogous, although not 
in the same situation, to the gular pouch of the male Bustard. 
The larynx frequently has membranous pouches in connection 
with it, into which air passes. These may be lateral and opening 
just above the vocal cords, when they constitute the sacculi laryngis, 
found -in a rudimentary state in Man, and attaining an enormous 
development, so as to reach to the shoulders and axille, in some 
of the Anthropoid Apes; or they may be median, opening in 
front either above or below the thyroid and cricoid cartilages, as in 
the Howling and other Monkeys, and also in the Whalebone 
Whales and Great Anteater. 
Urinary Organs.—The kidneys of mammals are more compact 
and definite in form than in other vertebrates, being usually more 
or less oval, with an indent on the side turned towards the middle 
line, from and into which the vessels and ducts pass. They are 
distinctly divided into a cortical secretory portion, composed 
mainly of convoluted tubes, and containing the so-called Malpighian 
bodies ; and a medullary excreting portion, formed of straight tubes 
converging towards a papilla, embraced by the commencement of 
the ureter or duct of the organ. The kidneys of some mammals, 
as most Monkeys, Carnivores, Rodents, etc, are simple, with a 
single papilla into which all the renal tubuli enter. In others, as 
Man, there are many pyramids of the medullary portion, each with 
its papilla, opening into a division (calyx) of the upper end of the 
ureter. Such kidneys, either in the embryonic condition only, or 
throughout life, are lobulated on the surface. In some cases, as in 
Bears, Seals, and especially the Cetacea, the lobulation is carried 
further, the whole organ being composed of a mass of renules, 
loosely united by connective tissue, and with separate ducts, which 
soon join to form the common ureter. 
Bladder.—In all mammals except the Monotremes the ureters 
terminate by slit-like valvular openings in the urinary bladder. 
This receptacle when filled discharges its contents through the 
single median urethra, which in the male is almost invariably 
included in the penis, and in the females of some species of Rodents, 
Insectivores, and Lemurs has a similar relation to the clitoris. In 
the Monotremes, though the bladder is present, the ureters do not 
enter into it, but join the urino-genital canal some distance below 
‘it, with the orifice of the genital duct intervening. 
VI. NERVOUS SYSTEM AND ORGANS OF SENSE. 
Brain.—The brain of mammals shows a higher condition of 
organisation than that of other vertebrates. The cerebral hemi- 
