21 
mouths of great livers for the purposes of respiration, and landing on the sand, 
during the night, to deposit its ova. The individual from which the pre¬ 
sent description is taken, weighed about 175lbs., the heart, when removed from 
the body, and emptied of its blood, was about the size of a large lamb’s heart, and 
pulsated for six hours after death; the contractions of the heart, after they had 
apparently ceased, might easily be excited again by pricking it with the point 
of a needle. This excitability continued during three or four hours more. 
The heart of this order of reptiles is composed of four cavities, like those of 
the mammalia and birds ; two of the cavities receiving the blood from the body 
and lungs, the other two propelling it forward into the lungs, and to the system 
generally. Man and the higher orders of animals, as mammals and birds, have a 
perfect double circulation, the heart consisting of four distinct and separate cavi¬ 
ties ; two, the receiving parts, termed auricles, the propelling ones, called ventri¬ 
cles. The reptilia (of which the Turtles and Tortoises form the first order) have 
a circulation performed by an organ of a different anatomical construction : in 
these animals the cavities are still four-fold, but the cavities of the ventri¬ 
cles are not distinct from each other; they have communications through which 
the blood returning from the body generally, and that received from the lungs, are 
intermixed, and consequently an imperfectly decarbonized fluid is sent to the eco¬ 
nomy at large. The heart of the Testudo my das, of which a general view is 
given in Fig. 1, is composed of two auricles and two ventricles, a b and c d, like 
Fig. 1. 
Fig. 2. 
Fig. 1.—A front view of the heart, with the cavities of the right and left ventricles laid 
open. a. The right auricle, b. The left auricle, c. The right ventricle, d. The 
left ventricle, e. The pulmonary arteries, f. The aortae, three in number; one 
destined to supply the head, neck, and fore limbs, the remaining two uniting to sup¬ 
ply the posterior half of the body. 
Fig. 2—A back view of the heart, with the fissures, which mark the opening of the 
veins, returning the blood from the body and the lungs, a. The opening of the veins 
of the lungs into the left auricle, b. The opening of the venae cavae returning the 
blood from the body to the right auricle. 
