286 PLECTOGNATHI. TETRAODONTID^. 
of the body so abrupt, that the observer is apt 
to imagine that he looks upon the anterior half 
of a fish, cut across through its middle. These 
are fishes of gigantic size, which are sometimes 
taken in the British seas. 
About a hundred species are enumerated as 
belonging to the Family, the great majority of 
which are confined to the warm parts of the 
ocean. All are, we believe, marine in their 
habits. 
Genus Tetraodon. (Linn.) 
A depressed line, passing down the front of the 
aggregated teeth in both jaws, gives to the fishes 
of this genus the appearance of possessing four 
great teeth, two above and two below, whence 
the generic appellation. The body, either wholly 
or at least on the under parts, is studded with 
prickles, varying in size and in number. In 
some species, indeed, these are so small and so 
imbedded in the soft mucous skin, as not to be 
perceptible in a living state, but drying or pre- 
servation in spirit reveals them. 
The species of this genus,” observes Dr. 
Roget, are remarkable for being provided with 
the means of suddenly assuming a globular form 
by swallowing air, which passing into the crop 
or first stomach, blows up the whole animal like 
a balloon. The abdominal region being thus 
rendered the lightest, the body turns over, the 
stomach being the uppermost part, and the fish 
fioats upon its back, without having the power 
of directing itself during the state of forced dis- 
tension. But it is while thus bloated and pas- 
