HORKR. 
413 
acute the faculties of smell and taste, and perhaps in directing 
the inhaled current of water. At the hindmost half of the 
gullet there are six small openings, regularly arranged on each 
side, which communicate each by a tube with an equal numbel 
of membranous vesicles, a little compressed, and of the diameter 
of the fifth or sixth of an inch, the lining of each of which 
forms considerable folds, which serve in the place of gill-plates 
for performing the function of breathing; the water passing 
from the gullet through these tubes to the vesicles or gills, 
and from them, on each side by passages uniting into a tube, 
the water is discharged by a couple of ojienings, close to each 
other on the belly; and which therefore are truly the breathing 
holes or external gills, and taken as a whole nothing can be 
more wisely contrived for keeping in store and supplying the 
necessary fluid in a creature which occasionally for a long time 
cannot obtain a renewal of the same from without. These 
outward openings of the breathing organs are behind the muscular 
apparatus of the tongue, which is large and turned far backtvard, 
reaching from the gullet to the openings, and in thickness is 
equal to half the diameter of the body; its action being directed 
by several powerful muscles, which, with the help of the grating 
teeth, will act on the food like a file, while the single tooth 
on the palate is emifloyed in fixing the mouth of the devourer 
on its prey; a structure and action not much unlike what is 
common in a large portion of osseous fishes. 
Mr. Owen remarks that the whole of the anterior parts, as 
the muscles and integuments of the head, the barbs, nasal tube, 
membrane lining the mouth and tongue, and the teeth in 
the throat, with the pharynx or passage leading to the gullet, 
are furnished Avith one common nerve, termed the fifth pair^ 
from which they obtain a high degree of sensation of a peculiar 
kind. And singular, as well as cfl^cctual, as this inward orga- 
nization appears to be for the special habits of this fish, the 
structm-e of the spine seems scarcely less so as compared Avith 
that of other fishes, but as such suggesting an opinion of a 
very low degree of intelligence. Connected with this Dr. 
Eoget observes, in his Bridgewater Treatise,— “There are few 
parts in the structure of animals that exhibit more remarkable 
instances of the laAV of gradation than the spine of fishes, in 
AAdiich we may trace a regular progression of development. 
