COMMERSONIAN TRIPLE-TAIL* 79 



of a single incisive and triangular tooth, no others 

 being observable either on the palate or tongue, 

 which latter is very short, cartilaginous, but rather 

 fleshy at the tip, which is rounded : the nostrils are 

 very small, and placed nearer to the eyes than to 

 the tip of the snout : the eyes are moderately large, 

 slightly convex, not covered by the common skin, 

 as in the Gymnotes and some other apodal fishes, 

 and the irides are of a bright gold and silver colour : 

 the gill-covers are situated beneath the skin, and 

 are each composed of an osseous lamina in form of 

 a sickle : the gill-membrane is five-rayed, and is at- 

 tached to the head or body round its whole con- 

 tour, in such a manner as to leave but a small 

 orifice just beyond the snout ; in which respect it 

 appears analogous to the Syngnathi or Sea-Needles, 

 as well as to the Callyonimi and some other fishes ; 

 but what renders the Triurus most remarkable is, a 

 particularity of which we find no example in the 

 whole class of Pisces : this consists in a soft, fleshy, 

 lunated valvule, attached to the anterior edge of 

 the branchial orifice, which it closes at the pleasure 

 of the animal, by applying itself to the posterior 

 edge : the body is not marked by any lateral line ; the 

 belly is terminated beneath by a sharp keel almost 

 throughout its whole length, and the vent is situated 

 at the extremity of the abdomen : the pectoral fins 

 are small, delicate, transparent, of an almost tri- 

 angular form when expanded, and have twelve or 

 thirteen rays : the vent-fin has fifteen soft rays, and 

 is directed backwards, its sharp end stretching al- 

 most as far as the posterior edge of the tail-fin, of 



