92 A HISTORY OF FISHES 



have fins and scales ye shall eat; and whatsoever hath not fins 

 and scales ye shall not eat; it is unclean unto you" had a 

 certain practical object, for it excluded all the Cat-fishes, which, 

 although pleasant to the palate, were known to be unwhole- 

 some and to cause diarrhoea and skin eruptions. These strict 

 laws, forbidding as they did many plentiful and tasty species, 

 naturally became gradually modified; fish with "at least two 

 scales and one fin" were soon permitted, and, finally, any part 

 of any fish on which traces of scales were visible ! 



The Dab (Limanda), with its ctenoid scales on the upper 

 surface and cycloid scales below, has already been described. 

 In other Flat-fishes the scales on the middle of the upper side 

 are smooth, those on the head and near the edges of the body 

 being spinate. In the Flounder [Flesus) most of the scales on the 

 head, in the region of the lateral line, and also a series along 

 the bases of the dorsal and anal fins, have been transformed into 

 little thorny tubercles, generally stronger on the coloured side 

 of the fish (Fig. 8b) ; the remainder of the body is covered with 

 embedded cycloid scales, but in an allied species, the Diamond 

 Flounder {Platichthys) of the Pacific coast of North America, 

 these have been almost entirely suppressed, and the whole of 

 the head and body is armed with irregularly scattered spiny 

 tubercles (Fig. 40A). In another related form from Japan 

 (Kareius) the tubercles are aggregated into clusters, and take 

 the form of bony patches of varying size (Fig. 40c) . In another 

 group of Flat-fishes {Bothidae) the closely related Turbot 

 {Rhombus maximus) and Brill {R. laevis) have quite diflferent 

 forms of scaly covering. In the Brill the body is armed with 

 small cycloid scales, which are more or less overlapping, 

 whereas the Turbot has a naked skin, but the coloured side 

 bears a number of small, scattered, bony tubercles. The Black 

 Sea Turbot {R. maeoticus), a distinct species, has very much larger 

 tubercles, and these are developed on the lower as well as on the 

 upper surface (Fig. 40B). Among other fishes with a somewhat 

 similar armature, mention may be made of the Lump-sucker 

 (Oyclopierus) , whose thick skin is studded with bony warts, some of 

 which are enlarged to form a series of cone-like projections along 

 the back and three rows on either side of the body (Fig. 35A). 



Two domesticated varieties of the Common Carp {Cyprinus 

 carpio) produced by continental fish-culturists may be briefly 

 described, since both these artificial forms exhibit modifications 

 of the normal scaling. In the Mirror Carp [Spiegelkarpfen) there 

 are one or two series of relatively enormous scales along the 



