( * 7 ? ) 
If this Animal be opened alive, you have the fatisfa- 
&ion to fee the Circulation of the Blood, by reafon of 
the tranfparency of the Membranes of the Veins, and 
the Alternative Motions, or Dilatations of the Heart 
and Auricles, and the Arteries and Veins, which are very 
flow in this Animal. 
From the Bafis of the Heart pafs out four great 
Arteries, that appear diftinCtly feparated one from the 
other 5 whereas in that of the Sea Tort oife, thefe Ar- 
teries are involved, for the length of an Inch, in a cap- 
ful a common to them all, which maketh them to appear 
I as if they were but one Trunk. If thefe four Arteries 
be entirely cut, the Heart is no more fufpended, but by 
I the conjunction of the two mttfculous Conduits of the 
I Auricles , which pierce the Heart in its pojierior part, to- 
i wards the middle of the Heart, on the Left fide, by 
which the Blood runneth from the Auricles into the 
Ventricle of the Heart. 
Thefe Arteries being thus divided, and the Heart 
turned ovef, the Auricles appear lying tranfverfely againfr 
the Back, in the capacity of the Pericardium : They make 
but one continued flefhy Body, a little extended, about 
two thirds inclining to the Left fide. Tis in this Bo- 
dy that the Cavities of the Auricles are feparated the 
one from the other, by a mufcular Septum , ficuated In- 
ternally to that Place, which appears contracted Exter- 
nally. Thefe Auricles make a mufcular Production about 
fix Lines long, which uniteth them to the Heart, to- 
i -wards the middle and left of its backfide. This Pro- 
duction is compofed of two Conduits, feparated only 
from one another by the Extenfion of the Septum, 
! which divideth the two Auricles : It is by thefe two 
Conduits that the Blood floweth from the Auricles into 
the ! Heart- The Body of thefe Auricles hath no ad- 
herence to the Pericardium , nor any fupport but that 
of the Veins, which end in it * for if you divide thefe 
Z Veins, 
