480 Kneeland’s Dissection of 
The heart was enclosed in a pericardiac cavity, separated 
from the abdominal cavity by the membranous diaphragm: 
the apex was not adherent. The blood is first received into 
a large sinus, with evident muscular fibres; it passes thence 
into the auricle, through an opening guarded by two valves, 
each an inch in length, having also muscular fibres. The 
auricle measured 2 inches in every diameter: the parietes 
about a line in thickness; muscular fibres numerous but del- 
icate: the auriculo-ventricular orifice cut open, measured 23 
inches, guarded by two equal valves. The ventricle was less 
capacious than the auricle ; the walls very strong and muscular, 
one third of an inch thick. The entrance into the branchial 
artery, cut open, was 12 inches. The commencement of this 
artery very thick and muscular for a length of 24 inches, the 
walls being three lines in thickness; this portion, which 
Cuvier has called “ the bulb,” measured, cut open, 12 inches. 
The bulb presents a double system of valves. 
- Cuvier, in his Comparative Anatomy, mentions the occur- 
rence of valves in the * bulbus arteriosus” of the cartilagin- 
ous fishes; but he gives no particular description of them. 
In an elaborate article by Miiller, (Abhandlungen der Akade- 
mie der Wissenschaften zu Berlin, 1844,) it is said (page 125) 
that the higher cartilaginous fishes are distinguished from the 
osseous fishes by the occurrence in the “bulbus arteriosus” 
of three or more longitudinal rows of valves, the number o 
valves in each row varying from two to five, according to the 
species." On page 126, it is stated that in the rays and sharks 
their number is never more than fifteen, (in Raia, Myliobatis, 
Pteroplatea, Scymnus, Squatina.) 
e first system extends upwards about an inch from the 
ventricular opening ; it consists of three principal longitudi- 
nal bands of fleshy valves, resembling vegetations, with one 
or two smaller rows between each two large ones; each lon" 
gitudinal band contained four valves, one above the other , 
like the steps of a ladder, when open: numerous delicate 
fleshy bands extended from the apex of one valve to the base 
