320 Sir Everard Home on 
from one another. This is not met with in any other animal, 
and it is at first difficult to account for it, as the circulation 
of the blood does not differ from that of the whale tribe and 
quadrupeds in general. 
It was natural to look to the heart of the whale for some- 
thing at least analogous to it. In the whale, the right ven- 
tricle has its apex on the same line with that of the left, and 
the muscular fibres appear to be more nearly of the same 
length, than in the hearts of quadrupeds in general. This 
circumstance, of the muscular coats of the two ventricles of 
the whale’s heart being more equal in power than is usual, 
renders it probable, that in the dugong, where the lungs have 
such uncommon length, it wa-s necessary that the approach 
to equality between the two ventricles should be still greater ; 
and this equality could in no way be so well effected as by 
giving the muscles of the right all the superior mechanical 
advantages which, in other animals, belong to the left, as was 
explained to the Society in the year 1790. 
The ventricles, although similaV in structure, are not of 
the same size or thickness ; the left in the larger dugong, is 
five inches long, and thicker than the right, which is only 
four and a half. 
The auricles have transverse elastic bands, passing from 
one side to the other, as in the whale. The orifice of the 
foramen ovale was completely closed, although the part 
where it had been, was distinctly marked. The valvulas 
mitrales and tricuspides had nothing particular in their ap- 
pearance; nor had the semilunar valves of the aorta and 
pulmonary artery. 
The relative size of these two great trunks is the same as 
in the elephant. 
