114 Kneeland on the Anatomy of Crocodilus lucius. 
(at least while the animal breathes in the air,) the posterior 
half receives only a mixed arterial and venous blood: - 
mingling of the two bloods taking place, not in the p 
itself, but by an opening between the two aortas. f 
was unknown to naturalists till the time of Meckel an 
Panizza. 
"Cuvier! says there is but one ventricle, divided into pr 
compartments : one, inferior and right, which receives the blo : 
of the right auricle and sends it to the left aorta ; a secon 
at the middle of the base of the heart, the smallest, in which 
is the opening of the pulmonary artery ; a third, superior and 
left, receiving the blood from the left auricle and sending 1t to 
the true aorta. He says distinctly that blood may pass from 
the right to the left apartments by filtering through the holes 
in their partitions. This last he maintains in his second edi- 
tion, though he confesses he has some doubts on the point. 
In a note, it is said that M. Martin St. Ange, as early as 
1829, made two ventricles, with no communication between 
them; after him Meckel, in 1831, and Panizza, in 1833, 
maintained that there was no communication between them. 
Milne Edwards? says that in the crocodiles there is a com- 
. plete separation between the ventricles, and that the arterial 
and venous bloods are not mixed until they arrive at the de- 
scending aorta; he makes no mention of an opening between 
the two aortas. 
Both Meckel and Panizza say, that from the right ventricle 
arise the left aorta and the pulmonary artery, and from the 
left ventricle the right aorta. Müller, Bischoff, and Mayer 
confirm Meckel’s description. 
Mr. Hentz? allows that two vessels arise from the right 
ventricle, but he also says that both aortas arise from the left 
ventricle: he mentions the opening between the aortas. 
* Leçons d’Anatomie Comparée. Paris: 1839, Vol. 6, pp. 312, et seq. 
`% Elemens de Zoölogie. Paris: 1894. 
y re of the American Philosophical Society, Philadelphia. 1825. No. 10, 
p. <19. 
