Side, and goes out of this fame Ventricle, by the three 
Holes which are on the. Right Side. 
The fecond thing remarkable in this Ventricle is 
the Fibres of the Heart. They are of two forts 5 fome 
are External, difpofed under the common Membrane in 
feveral Plans, very fmali, but obliquely circular, extend- 
ing from the Ba/is , but particularly about the Arteries, 
which ferve them inftead of Tendons or Points of 
fupport, towards the Inferior Circumference of the 
Heart : The other Mufculous Fibres which compofe the 
Heart, are in the manner of feveral Columns, asthofe- 1 ' 
of the Human Hearr * they are fituated Internally in 
both fides, lying obliquely from the Right, where their 
Tendons are about the Arteries, to the Left * which 
demonftrates that their attion is from the Left to the 
Right Side, where the Orifices of the Arteries lye open* 
to let the Blood pafs our. 
It has been (aid before, that the two Auricles of the 
Heart of theLandTortoife of America, make Externally but 
one continued Body 5 but that it has Internally two Cavi- 
ties, feparated from one another by a Mufculous Septum. 
This Septum feparates them fo exattly, that there is cot 
the leaft Communication of the one with the other- 
fo that the Blood of either Auricle does not mix with 
that of the other, but in the Ventricle of the Heart. 
The Right Auricle is as big again as the Left • ali 
the Blood of the Animal (that of the Lungs excepted ) ] 
pafiing through it to go into the Heart* the Lefr Au- 
ricle receiving only the Blood which cometh from the 
Lungs, the Pulmonary Veins being very fmull. The 
Internal Part, of the Auricles are furnilhed with little 
Mufculous Columns, but particularly at their Extremi- 
ties, fituated in fuch a manner, that it is vifible their 
aaion tends to pulh the Blood againft the Septum 
where the Conduits, which convey it into the Heart* 
sre fituated , - ' ^ ' v* - 
There 
