PLECTOGNATHI. 271 



Others have short spines, proceeding from three diverging 

 roots.(l) 



Some again have spines as slender as pins or hairs. (2) 



Tetraodon, Lin. 



Jaws divided in the middle by a suture, so as to present the appear- 

 ance of four teeth, two above and two below; spines small and low. 

 Several species are said to be poisonous. 



T. lineatus^ L. ; Fahaca of the Arabs; Fiasco psaro of the 



Greeks; T. physa, Geoff., Poiss. d'Egypt., I, 1; Rondel. 419. 



Back and flank longitudinally striped with brown and whitish. 



From the Nile, which, during its inundations, casts thousands 



of them on shore, where they serve as play things for the 



children. 

 Some of them have a laterally compressed body, and a somewhat 

 trenchant back; their power of inflation must be less than the others. 

 One of them is electrical. (3) 



Mus., IV, p. 134, Seb., Ill, xxiv, 10; — Biod. triedricus, Cuv., Mem. Mus. IV, p. 

 133, Seb., II, xxiii, 4; — B. nidemerus, Cuv., loc. cit., IV, vii, 5; — B. novem-mac~ 

 ulatus. Id., lb., VI, 3; — B. sex-maculaius, Id., lb., VII, 1; — B. multimaculatus. 

 Id., lb., 4. 



(1) Biod. tigrinus, Cuv., Mem. Mus., IV, vi, 1, or orhiculatus, Bl., 127, Seb., 

 Ill, xxiii, 3; — B. rivulatus, Cuv., lb., 2, or maculato-striatus, Mitch., VI, 3, pro- 

 bably the Orbe, Lacep., I, xxiv, 3; — B.jacuUferus, Cuv., loc. cit., VII, 3; — B. an- 

 tennatus, Id. lb., 2. 



(2) Biod. jotVosws, "Mitchil., I, 471. 



(3) The head and tail of the fishes of this genus are generally smooth, but the 

 rest of their body is rendered more or less rough, by the very small spines which 

 arise from the skin. The various combinations of the smooth and ro\igh parts, 

 and the different configurations resulting from the more or less oblique form of 

 their head, have allowed me to arrange them in the following manner: 



I. Species with a short head, possessing the faculty of inflating themselves so 

 as to attain a globular form. 

 1st. The entire body rough. 



A. Immaculate; — Tetr. immaculatus, Lacep., I, xxiv, 1, Russel^ I, 26. 



B. With black spots; — Tetr. mouchele, Lacep., 1, xxv, i, or T. Commersonii, 

 Schn., Russ., 1,28; — Tetr. _/uuta/t7i5, Buchan, XXX, 1; — Tetr. geometricus, Bl.,. 

 Schn., Catesb., II, xxviii. 



C. With black bands; — Tetr. fahaca, or T. physa, Geoff., Poiss. d'Eg., I, 1; — 

 T. lineatus, Bl., 141, to which the Tetr. psiltatus, BL, Schn., 95, is at least closely 

 allied. 



D. With pale spots; — Tetr. testudineus, Bl., 139, of which the T. reticularis, Bl., 

 Schn., appears to be a variety; — T. hispidus, Lacep., I, xxiv, 2, and Geoff. Poiss., 

 d'Eg., [, 2;—T. patoca, Buchan, XVIII, 2. 



2d. The entire body smooth: T. Ixvissimus, Bl., Schn.; — T. cutcutia, Buchan., 

 XIIT, 3. 



