ORDER VI. 



PLECTOGNATHI. 



Family I. 

 GYMNODONTES. 



Tetraodon. Lin. 



Generic characters. Both jaivs divided in the middle hy a 

 suture, producing the appearance of four teeth in front, tioo 

 above and two helow. The skin over part of the body, armed 

 with numei'ous short spines. The branchial orifice small. 



T. turgidus. Mitchell. The Swell Fish. Puffer. 

 Trans. Lit. et Philosoph. Soc. N. Y. vol i. p. 473, et fig. 



This very curious fish, which receives its name from its 

 power of inflating itself to a surprising degree with air, was 

 first described by Mitchell. His description of the fish itself 

 is rather indefinite, and his figure is not scientifically accurate. 

 He says : " Length about 12 or 14 inches ; depth less than two 

 inches, and breadth about two inches ; but the belly is loose 

 and flabby ; and it may be distended to a large size, apparently 

 at the will of the fish." "With yellowish variegated back, 

 white, rough belly, and a remarkable propensity to distend the 

 abdominal sac with air, when he is out of water." The figure 

 accompanying this description represents the species as having 

 the back rough from just back of the eyes to the caudal fin ; 

 and the space between the eyes and the extremity of the snout, 

 smooth. Of the two specimens I have had an opportunity of 

 examining, one was eight inches in length ; the other, nine 

 inches. The former was taken in Boston harbor. From the 

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