Plectognatiis.- 



-FISHES.- 



-Gymnodonts. 



159 



tiired. It is an inhabitant also of the Mediterranean, 

 Atlantic, and Indian Ocean. — Plate 13, fig. C5. 



FiR. 45. 



Gilded Trigger-fish (Xanthichthys curassavicns). 



The Balistids and CofFev-fishes, or Ostracionids, con- 

 si itnte the family of Sderodermes of Cuvier. 



Family II.— OSTRACIONIDS {Ontmcionidw). 

 Plate 13, fig. G6. 



Those CoFFER-FisiiES liave the body inclosed in a 

 tesselated cuirass of scales arranged qnincunciall}', 

 forming a box of little or no flexibility, from out of 

 wliich the lips, teeth, pectorals, and tail with its three 

 vertical fins protrude. The pelvic bones and ventrals 

 are wanting. The vertebraj of the belly are mostly 

 coalcsccnt, and the body has but liltle muscular sub- 

 stance, its motions being limited. Exteriorly the gill- 



opening is only a short slit, bordered by a skinny edge, 

 but interiorly it has an operculum and six branchio- 

 stegals. The box-like mail is in 

 some species rectangular ; in others 

 triangular in section, or it is oval or 

 orbicular. The liver is large and 

 oily ; tlie stomach capacious and 

 membranaceous. 



The genera are — Cihotion-^ Do^ijopln-y^; 

 Osiraclon; Aracana; and Ccnfaunts. — (.Si'u 

 Kaup, Cut. Brit, ilus.) 



Family III.— GYMNODONTS 



( Gymnodonl'uhi:) . 



Plate 13, figs. G7, C8. 



This family, characterized by Cuvier 

 under the name of Gymnodonts, com- 

 prises his Diodonts, Tdrodonls, Trio- 

 donts, and Mules or Sun-fish. Its 

 members have the teeth incorporated 

 in the gorget- shaped jaws, forming a 

 bill like that of a parrot. Cuvier's 

 genera have been desoibcd by Dr. 

 Kanp as families or sub-families. 

 The DionoNTS have a flexible skin which, in most 

 species, is iaflatible so as to give a globular shape to 

 tlio fish, and is armed with spines which diverge every 

 way when tlie skin is distended. No mesial division 

 exists in either the upper or under jaw, each having 

 the form of a horse's hoof, with the teeth incorporated 

 in their bony substance. 



Tlie genera are — Diodon; Dicofi/llcftl/ti/s; Cheilomycterus ; 

 Cydichtliys ; and Cyanichthys; none of which are British. 



The MoLEBDTS or Sun-fisiies {Orthogoriichii) 

 have jaws like the Diodonts, and are compressed fishes 

 incapable of inflation, and a tail so short and high us to 

 seem as if docked oil'. The dorsal is high and pointed. 



Fig. 46. 



Turkey-fish (Tetraodon meleagris). 



and is united at the base to the caudal. No air-bladder 

 is present, and the small stomach is entered directly by 

 the bile-duct. The arterial stem is provided at its 



origin witli four semilunar valves. The skin is smooth 

 in some species, and in otliers is armed by scattered 

 spines. The myelon is greatly abbreviated. Tlie 



