122 



Proceediwjs of the Royal Irish Academy. 



Tradiyrhynclnis tracliyTliynchus (Eisso). 



Maerv/rws trackyrhyncTms, Giinther (1862), Yaillaiit (1883j. 



TracliyrhyncMis scabious, Goode and Bean (1895). 



Tracliyrhynchus trachyrJiynchv^s, Giinther (1887), Koehler (1896), Murray 



and Hjort (1912). 



(Plate YII, figs. 4, 8.) 



^ 



Fig. 10. — Trachyyhyuchus ifachyrhynehtis. 



Description. — Bod\' elongate, increasing very slight!}' f loui the head to the 

 first dorsal fin, and thence tapering gradually to a pointed tail. Body about 

 as wide as high at the first dorsal, and becoming slightly compressed in the 

 caudal region. 



Head contained about 3f times in the total length and produced into a 

 flattened pointed snout. A strong ridge, separating the upper and lower 

 surfaces of the head, runs from the snout to the operculum, passing close 

 beneath the eye. Ej'e about li times as long as high, and contained o\ times 

 in length of head. Head completely covered with small elongate scutes, each 

 with a denticulated ridge or "keel. The scutes are arranged so that their keels 

 unite to form elongated ridges converging towards the snout. The underside 

 of the head is covered with similar but smaller scutes with crests of from 3 to 

 6 cusps, the linear arrangement of scutes not being so evident as on the upper 

 surface of the head. Occipital fossa not very noticeable, hardly more than a 

 shallow depression between two ridges. Supra-orbital ridge almost obsolete. 

 Mouth inferior, hoi-seshoe-shaped. Barbel small. 



Body covered with stout scales. In a specimen of 24"0 cms. each scale has 

 a single strong backward-directed spine (PI. YII, fig. 8), except tliose of the 

 lateral line, which have two spines, one on each side of the channel. In a 

 larger specimen of •49-5 cms. the scales bear one large and, usually, two smaller 

 spines, short and robust, the whole scale being thickened and massive, and 

 the surface striae obliterated (PL Wl, fig. 4). The form of the scales differs 

 on different parts of the body ; on the sides they are much deeper than wide, 

 but towards the tail the difference in proportion diminishes, and in young 



