3^ 2 Mr. hunter^s Account of 
thoiu canals or cavities they mu ft be compofed of fuch fub- 
ftance as is capable of keeping its form. 
Each tube deferibes more than a femi-circle. This refembles 
el feme i cl pc ft what we find in mold other animals, but differs 
in the parts being dilrincf from the fkull *. 
Two of the femi-circular canals are ffmilar to one another, 
may be called a pair, and are placed perpendicularly ; the 
third is not fo long; in feme it is placed horizontally, uniting 
as it were the other two at their ends or terminations. In the 
fkait it is fomething different, being only united to one of the 
perpendiculars. 
ft he two perpendiculars unite at one part in one canal, by 
one arm of each uniting, while the other two arms or horns 
have no connedion with each other, and the arms of the hori- 
zontal unite with the other two arms of the perpendicular near 
the entrance into the common canal or cavity. 
hdeai the union of thole canals into the common, they are 
fwelled out into round bags, becoming there much larger. 
In the lay kind they all terminate in one cavity, as has been 
obferved ; and in the cod they terminate in one canal, which 
in thefe fifh is placed upon the additional cavity or cavities. In 
this cavity or cavities there is a bone or bones. In fome there 
are two bones ; as the jack has two cavities, we find in one 
of thofe cavities two bones, and in the other only one ; in the 
ray there is only a chalky lubftance f. 
At this union of the two perpendiculars in fome fiffi enters 
the external communication, or what may be called the external 
meatus. This is the cafe with all the ray kind, the external orifice 
The turtle and the crocodile have a ftru&ure fomewhat fimilar to this ; and 
rhe intention is the fame, for their Ik.ills make no part of the organ, 
i This chalky fubrtance is alfo found in the ears of amphibious animals. 
of 
