494 ZOOLOGY. 
bellum is small, especially in the serpents. In the croco- 
diles the brain most approaches that of birds, the cerebellum 
being larger than usual in the middle, and in this respect 
somewhat approaching the birds.* Corpora striata (which 
are thickenings of the outer walls of the cerebral hemispheres) 
and the anterior commissure of the cerebral hemispheres are 
present for the first time in the vertebrate series. 
The kidneys (Fig. 440, &) are lobulated, varying in form 
and position, and usually situated near the cloaca, the ureters 
being short and opening into the cloaca. The reproductive 
organs are generally like those of the Batrachians.. The 
ovaries lie on each side of the vertebral column, and vary in 
size with the season, being largest during the time of repro- 
duction. The oviducts (Fig. 440, 2) are voluminous coiled 
‘canals, which in most reptiles open into the cloaca; in the 
turtles, however, opening into the neck of the so-called 
urinary bladder. After the egg passes into the oviduct it 
is enveloped by the ‘‘ white” or albumen, which is secreted 
in the anterior part of the oviduct, while the thick-walled 
terminal part secretes the shell. 
The external differences between the sexes is more marked 
than in the Amphibians. According to Darwin, the sexes of 
the Chelonians and snakes differ very slightly ; male rattle- 
snakes are said to be more yellow; in the Hast Indian Dip- 
sas cynodon the male is bright green, while the female is 
bronze-colored. Male lizards are usually larger, while male 
snakes are always smaller than those of the opposite sex. 
Various appendages, such as crests, warts, horns, etc., when 
present in both sexes, ate most developed in the males, 
while the colors and markings are brighter in the latter sex, 
The moulting of the skin is effected by its being pushed off 
by the upward growth of fine, temporary cuticular hairs. 
‘On certain parts of the body, as on the underside of the 
capsular skin and scales of the eyes, these hairs do not de- 
velop. After the skin is loosened, it dries and is readily 
shuffled off. 
The eggs of turtles, like those of birds, are very large, 
the yolk mass being greatly developed. The lizards, snakes, 
and crocodiles lay their eggs in sand or light soil, while those 
* Stegosaurus had the smallest brain proportionally of any land 
vertebrate. 
