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 w^holly 

 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 

 floats 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- 



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