NOMENCLATURE AND MORPHOLOGY. 117 



in the lower jaw, but two circular openings of canals in the 

 bone are visible through the dried skin which covers them. 

 The opposing surfaces of the intermaxillaries and lower jaw are 

 covered with densely-crowded, curved, fine card-like teeth, or 

 as they ought, perhaps, to be called, in conformity with Cuvier's 

 nomenclature, rather coarse "dents en velours;" the dental sur- 

 face being broad anteriorly and narrowing to a point behind ; 

 the transverse, anterior, projecting extremity of the vomer and 

 the outer edges of the palate bones are armed with fine teeth " en 

 velours ; " the dental surface of the latter narrowing to a point, 

 posteriorly, like those of the mandibles ; there is, however, a de- 

 tached but contiguous patch just beyond this point on the edge of 

 the palate ; the whole vault of the palate is smooth ; the tongue, as 

 we have already mentioned, has been removed, and if Mr. Todd's 

 account of the pharyngeal teeth be correct, they are not distributed 

 into the same number of patches as in the perch. Preoperculum 

 having a narrow upright limb, covered with smooth skin, there 

 being a single scale only just above its angle ; the lower limb is 

 wider and has three scales in a single row which does not cover 

 half its surface ; the whole edge of the bone is smooth and even, 

 with the exception of a very shallow, wide notch at the base of 

 the upper limb. The interoperculum is comparatively broad, its 

 depth exceeding that of either the preoperculum or suboperculum, 

 it is covered by a row of ten scales, which leave its under border 

 naked ; the bony operculum has an acute oblique notch in its 

 posterior margin, producing two thin points ; the lower point is 

 closely applied to the apex of the suboperculum, forming with it 

 one obtuse thin plate, which, together with the upper point, 

 are concealed by the membrane which borders them ; the under 

 margin of the suboperculum is slightly waved, forming two ob- 

 scure lobes ; as in many, or perhaps in most of the percoidese 

 with scaly gill covers, the margins of the pieces composing them 

 are covered with a smooth skin; there is even a wider naked 

 place than usual behind the points of the operculum, and the 



