FAMILY GYMNODONTID^. 327 



GENUS TETRAODON. Linneus. 



Both jaws divided in the middle by a suture, presenting the appearance of four teeth, two 

 above and two beneath. The surface either entirely or partially covered with prickles. 

 Form often globular. 



Obs. This genus, like the preceding, has the property of inflating itself by swallowing air. 

 When captured, they produce a sound which is caused by the rapid emission of the air. Some 

 species are electrical. It comprises many species, which are susceptible of numerous sub- 

 divisions. 



THE COMMON PUFFER. 



Tetraodon tubgidcj. 



PLATE LV. FIG. 178. i 



Tetndon hiapidus. Linneus. 



Taid-fUh at New-York. ScHCEPFF, Beobachtungen, Vol. 8, p. 189. 



Puffer, Tetrodm tUTgidus. MlTCHiLL, Trans. Lit. and Phil. Soc. Vol. 1, p. 473, pi. 6, fig. 5. 



TetTcadon turgidus, SuxU-fish, Puffer. Stoeeb, Report on the Fishes of Massachusetts, p. 169. 



Characteristics. The whole surface roughened with prickles, except the chin and the space 

 posterior to the dorsal and anal fins. Olive-green above ; white beneath. 

 Length six to twelve inches. 



Description. Body oblong, cylindrical ; when inflated, nearly globular. The whole sur- 

 face, with the exceptions noted in the specific phrase, and small spaces around the nostrils 

 and behind the pectorals, thickly covered with small acute prickles with a trifid base ; these 

 prickles are more closely sprinkled on the back and the space between the eyes. The smooth 

 surface on the posterior part of the body advances slightly before the dorsal and anal fins, and 

 still more on the sides. No trace of a lateral line. Head scarcely distinct from the body. 

 Branchial aperture, a narrow sublunate slit in front of the pectorals. Eyes large, longitudi- 

 nally oval ; the greatest diameter 0'6, and the distance of the orbits apart slightly exceeding 

 their diameters ; the space between them, plane, sloping with a slight concavity to the jaws. 

 Nostrils with a short filament, and nearer to the eyes than to the extremity of the snout ; a 

 small space around them, free from prickles and perfectly smooth. Jaws robust. 



The dorsal fin arises anterior to the base of the anal fin, fan-shaped, higher than broad, 

 with eight branched rays ; the first short and simple, the second highest, and thence gradually 

 diminishing to the last. Pectoral fins broad and rounded. Anal small and slender. Caudal 

 rounded. The membrane of all the rays very thin and delicate. 



Color. Above darkish olive green on the upper part of the head, body and tail, with a yel- 

 lowish tinge along the sides. Sides and all beneath white, with occasionally a greenish tinge. _ 

 Along the sides, from beneath the eye to the caudal fin,, is an indefinite series of six to eight 



