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Show 270 I>JSCES. · Two of the genera, Tetraodon and JJiodon, have the faculty of swelling themselves up like a balloon, by filling their sto· mach, or rather a sort of very thin and extensible crop, which occupies the whole length of the abdomen, and adheres closely to the peritoneum, a circumstance which has occasioned it to be considered at one time as the peritoneum itself, and at another as a species of epiploon, with air. When thus inflated, they roll over, and float on the surface, with the abdomen up· wards, unable to direct their course; but they are extremely well defended while in this position by the erection of the spines with which their skin is everywhere furnished.(!) Their nata tory bladder has two lobes, and their kidneys, which are placed very high up, have been erroneously taken for lungs.(2) They have but three branchirn on each side,(3) and when captured they produce a sound which is occasioned by the air rushing out of their stomach. Each of their nostrils is furnished with a double fleshy tentaculum. DIODON, Lin. So called because the jaws are undivided and formed of one piece above and another below. Behind the trenchant edge of each of these pieces, is a round portion, transversely furrowed, which con· stitutes a powerful instrument of mastication.( 4) The skin is every· where so armed with stout pointed spines, that when inflated, they resemble the burr of a chesnut tree. A number of species inhabit the seas of hot climates. Some of them have long spines supported by two lateral roots. The most common of this group, Diad. atinga, BL, \25, and better, Seb., III, xxiii, 1, '2 , is more than a foot in diameter.(5) (1) See Geoffl·oy-St-Hilaire, Poiss. d'Eg., in the great work on that country. A similar disposition is observable in Chironectes. (2) It is thus I explain the mistake of Schrepfer in the publications of the Nat. ()fBerlin, VIII, 190, and that of Plumier, Schn., 513, and doubtless that of Gar· .den, Lin. Syst., Eel. XII, i, p. 348. As to the cellular organs mentioned by Broussonnet, Ac. des Sc., 1780, last page, there is nothing to be found whic~ re· sembles them. The process of respirntion in these fishes is similar in all thmgs to that of others. (3) An instance of this we hnve already seen in Lophius. (4) Fossil jaws of this description are not uncommon. . (5) The Diod. hist1-ix, 'Bl., 126, is the same species uninfl.atcd. To avo'd.al 1 equivocation, I call it Diodon punctatus;-Add Diod. spinosissimua, Cuv., Mem. PLECTOGNATHI. 271 Others have short spines, proceedit1g from three diverging roots.( I) 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 appearance 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; Flasco psaro of the Greeks; T. physa, Geoff., Poiss. d'Egypt., I, 1; Randel. 419. Back and flank longitudinally striped with b1·own and whitish. F1·om the Nile, which, during its inundations, casts thousands of thl'..m. on shore, where they serve as play things for the children. Some of them have a laterally compressed body, and a somewhat trenchant back . :teir power of inflation must be less than the others. One of them is 1ec trical.( 3) Mus., IV, p . .J3A, Seb., III, xxiv, 10;-Diod. triedricus, Cuv., Mem. Mus. IV, p. 133, Seb., II, xxiii, 4;-D. nictemerus, Cuv., loc. cit., IV, vii, 5;-D. novem-mac· ulatus, Id., lb., VI, 3;-D. sex-mawlatus, Id., lb.,, VJT, 1;-D. multimaculatus, Id., lb., 4. (1) Diod. tigr-inus, Cuv., Mem. Mus., IV, vi, 1, or orbiculatus, Bl., 127, Seb., m, xxiii, 3;-D. rivulatus, Cuv., lb., 2, or maculato.striaftta, Mitch., VI, 3, probably the Orbe, Lacep., I, xxiv, 3;-D.jaculiferus, Cuv., loc. cit., Vll, 3;-D. antennatus, Id. lb., 2. (2) Diod. pilosas, 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 rongh parts, and the diffet·ent 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. D. With black spots;-Tetr. moue/tete, Lacep., I, xxv, i, or T. Commersonii, Schn., Russ., I, 28;-Tetr. fi'uviatilis, Buchan, XXX, 1;-Tetr. geometricus, Bl., Schn., Catesb., II, xxviii . C: With black bands;-Tetr. falwca, or T. pltysa, Geoff., Poiss. d'Eg., I, 1;T. lmeatus, Bl., 141, to which the Tetr. psittatus, Bl., Schn., 95, is at least closely allied. D. With pale spots;-7~tr. testudineus, BJ., 139, of which the T. reticularis, Bl., Schn., appears to be a variety;-T. ldspidus, Lacep., I, xxiv, 2, and Geoff. Poiss., d'Eg., I, 2;-T. patoc~ Buchan, XVlll, 2. 2d. The entire body smooth: T. lawissimus, B1., Schn.;-T. cutcutia, Buchan, xm,3. |