LECTURE X. 
129 
found in considerable quantities, cast on the 
shores, and forms a small article of commerce, 
being used for various purposes by different arti- 
ficers. It also serves, when reduced to powder, as 
a good common dentifrice, and is indeed con- 
sidered as one of the most innocent that can be 
used for that purpose. 
The anatomy of the Cuttle-Fish is highly 
curious, and has long ago been detailed by Swam- 
merdam and others ; and was even not unknown 
to the ancients. The animal is furnished with a 
pair of large lungs or respiratory organs, situated 
nearly as in quadrupeds, but they are constituted 
on a different principle, and are more allied to the 
gills of Fishes. The most striking particularity 
however in this animal is that of having three dis- 
tinct hearts : these are situated in the form of a 
triangle, and the lowest .of the three is larger than 
the rest. The eyes, which in this whole genus are 
remarkably large, are covered, as in Eels and some 
other fishes, by the common skin, which is trans- 
parent in those parts. The pupil of the eye appears 
double, and the internal cavity of the eye is lined 
with a purplish-coloured mucus, which causes the 
eyes of the living animal to appear phosphoric or 
LECT. II. 
K 
