374 



Survey of Fishing- Grounds, West Coast of Ireland, 1890-1891. 



serve to distinguish them, present the following features, as most clearly described 

 and illustrated {op. cit., PI. iii.) by Vaillant: — 



Type op Species. 



" Espece ty pique " (Vaillant), 

 Centrophore icailleux, Brouss. 

 C. Dumerili, Johns, [et auctorum). 



Colour — Brown, more or less mahogany. 



Fins. — Height of first dorsal nearly half the 

 length of its base ; height of second dorsal a half, 

 or less than half, the length of its base. 



Scales. — Lamella nearly as wide as long, lateral 

 keels strongly marked, posterior denticles fine, 

 numerous. 



Teeth. — In the ujiper jaw with narrow cusps ; 

 in the lower jaw with nearly vertical cusps ; a 

 median tooth present. 



Vaeiett. 



C. sguamosus, Giinther, Cat. {et auctorum). 



Colour. — Blackish-grey. 



Fins. — Height of first dorsal less than one-third 

 the length of its base ; height of second dorsal 

 more than half the length of its base. 



Scales. — Lamella considerably longer than wide, 

 lateral keels feeble, posterior denticles large and 

 few. 



Teeth. — In the upper jaw, with cusps forming 

 almost an equilateral triangle ; in the lower jaw, 

 with cusps strongly deflected outwards ; a median 

 tooth present or absent. 



It may be further stated that the spines of the dorsal fins are stouter and 

 more curved in the type than in the variety. 



We may be allowed to call attention to the well-known fact that the develop- 

 ment of a Plagiostomous fish is accompanied by very considerable changes in its 

 dermal armature, which, moreover, is frequently different in the sexes. It 

 follows, therefore, that great caution is required in distinguishing such species 

 as depend for their sej^aration chiefly on the characters of the scales and teeth. 

 Whether in the case of C sguamosus there is any marked difference in the 

 dentition of the two sexes is a matter as to which we have no information. All 

 Vaillant's specimens were males, as is also our own, and we have seen no 

 descrijDtion of a female (specially described as such). Hence we must admit 

 that possibly the diagnosis we have compiled may be applicable only to males. 



The pedunculate or sessile character of the scale has been made the basis of 

 a subdivision of the genus Centrophorus, which has not received much support 

 from subsequent authors. As Vaillant points out, even those species which 

 possess pedunculate scales have also sessile scales on some parts of their body ; 

 and we would even go further, and suggest that the pedunculate character cannot 

 even be applied as a specific test at all stages of develojjment. In the absence 

 of any knowledge of very young forms this is mere conjecture; but it appears 

 to us very possible that no member of the genus exhibits pedunculated scales 

 when very young. 



