€40 REPTILIA. - 
Into the right auricle venous blood is brought by the two superior 
venze cavee and by the inferior vena cava. The blood passes through 
a valved aperture into the right ventricle, and is driven thence—(a) by 
the pulmonary artery to either lung, or (4) by the left aortic arch to 
the body. From this left aortic arch, before it unites with its fellow 
on the right to form the dorsal aorta, is given off the great cceliac 
artery. The anterior viscera thus receive wholly venous blood from 
the heart. 
The blood driven to the lungs is purified there, and returns by pul- 
monary veins to the left auricle. Thence it passes through a valved 
aperture into the left ventricle. Thence it is driven into the right aortic 
arch, From this the carotids to the head and the subclavians to the 
fore-limbs are given off. These parts of the body thus receive wholly 
arterial blood from the heart. 
The venous blood returning from the posterior regions may pass 
through the kidneys in a renal-portal system, and thence into the 
inferior vena cava; or it may pass through the liver in a hepatic-portal 
system, and thence by hepatic veins into the inferior vena cava ; or some 
of it may pass directly into the inferior vena cava. The renal-portal 
veins arise from a transverse vessel uniting the two branches of the 
caudal, but the latter are also continued forward as lateral epigastrics 
which enter the liver. 
The temperature of the blood is not above that of the surrounding 
medium. 
In regard to the respiratory system, we should notice that the lungs 
are invested by pleural sacs, as is the case in Mammals. 
The ureters of the kidneys, the vasa deferentia from the testes in the 
male, the oviducts from the ovaries in the female, open into the cloaca, 
which has a longitudinal opening. The penis is on the anterior surface 
of the cloaca, 
The eggs, which in size are like those of geese, have a thin calcareous 
shell, are buried in excavated hollows, and, warmed by the sun, hatch 
without incubation. 
Of one species of crocodile it is known that the mother opens up the 
nest when the young, ready to be hatched, are heard to cry from 
within the eggs. The mothers take some care of the young, which 
require to be defended even from the appetite of the males, 
Crocodiles are relatively sluggish, and fond of basking passively, 
sometimes hiding in the mud during the hot season. They are remark: 
able for the long continuance of growth, which does not seem to have 
so definite a limit as in most other animals. 
Classification of Crocodilia 
(a) The true Crocodiles, of the genus Crocodilus, occur in Africa, 
Southern Asia, tropical Australia, Central America, and the West 
Indies. 
The Indian crocodile (C. porosus) may measure about 18 ft. in 
length, and even larger forms have been recorded. The sacred African 
