95 
and Structure of the Proteus Anguinus . 
vations, say the authors, not only illustrate certain facts regard- 
ing the proteus, but may apologise for those learned writers, 
who, from not having had the opportunity of dissecting this 
animal when recently dead, have deviated, in their anatomical 
descriptions, some little from the truth, 
5. Of the Organs of Circulation. 
The heart of the proteus is lodged in that triangular space 
which is formed by the branchial arches. Its situation and size may 
be seen in Plate VII. Fig. 1. Its structure is simple, consisting, 
like that of the frog, of one auricle and one ventricle. In figure, 
also, it resembles the heart of the frog, but is somewhat smaller 
in proportion. Its auricle is placed forward, and over the ven- 
tricle ; is slightly toothed on its margins ; and to the eye seems 
as large as the ventricle itself. 
From the base of the heart on the right side, springs a very 
short canal, which proceeds straightforward ; but before it gets 
beyond the auricle, by which it is covered, it expands into a 
bulbous form. This short canal, the only one that goes out from 
the heart, is of a soft fibrous texture, similar to that of the heart 
itself. The bulbous part, on the contrary, possesses great 
strength, and is opake and tendinous. Hence it is, that whe- 
ther it be empty or full of blood, it exhibits always a whitish 
pearly colour, different entirely from the other parts of the ves- 
sels, which, when full of blood, appear of a reddish or russet 
hue. 
From this bulb proceed two large arteries, which, almost imme- 
diately on quitting it, separate from each other, and are direct- 
ed, on either side, towards the branchial arches. These two ar- 
teries, for greater clearness and convenience of description, are 
called the two 'primary trunks ; but the authors will speak 
only of one, since what is said of one will apply equally to the 
other. 
Th e primary trunk, then, of the right side, very soon after quit- 
ting its fellow, gives off a branch which runs under the first arch 
through its whole length, where it sends off two arteries, one to 
the first gill, and the other to the muscles of the os hyoides ; af- 
terwards, abandoning the arch, and turning upward and inward, 
it goes to the roof of the occiput. This first branch from the 
