SORTATION. 



tion to the flat-fish generally so called. As the skates pass 

 through a shark stage in early life, so the flat-fish start as 

 very thin youngsters swimming the ordinary way up, with their 

 mouths like those of other fishes and their eyes in the normal 

 places, one on each side of the head ; but apparently, failing 

 to thrive under these conditions, they betake themselves to the 

 ground, where their exposed part takes on the colour of their 

 surroundings and their head turns over so as to bring both eyes on 

 the top, and, in some cases, their mouth becomes more developed 

 on one side than the other. 



In some cases they have subsided to the right, in others to the 

 left, and by this we know them. Holding them head foremost 

 towards us we have 



1. Eyes to the left. 



2. Eyes to the right. 



In the "eyes left " division are four genera. One, Arnoglossus, will 

 be found to have a couple of spines behind the left ventral ; there 

 being but one species, A. laterna, the scald-fish or 

 scald- back, so called from its skin rubbing off in 

 the trawl, as if it had been scalded. In the 

 other genera there are no spines behind the 

 ventrals. In one of them the tail is conspicuously 

 long, the fin by itself being the same length as the 

 distance between the ventral and the tip of the 

 snout ; this is Lepidorhombus, of which the only 

 species is L. megastoma, the megrim, which has not 

 only a large mouth but a large head and large eyes, 

 i SCALE. anc j a g enera i appearance of truculency which is 

 not prepossessing. The scales are " ctenoid," 

 that is, have a comb-like arrangement of teeth on the hinder edge, 

 much the same as that in the illustration (Fig. 6), which, however, 

 was not grown on a " merlry sole," as the megrim is occasionally 

 called on account of its activity when on a cruise. The other 

 genera have short tails. One, Zeugopterus, has ctenoid scales ; the 

 root of the tail is not free of the 

 other fins, and the dorsal and ventrals 

 are very long. There are two species, 

 Z. unimaculatus and Z.punctatus,both 

 known as topknots, the first being the 

 one spotted, the other the browny. 

 A third, known as the Norwegian 

 topknot, seems to be a variety hardly 

 worth mentioning, and, indeed, the 

 topknots are of little importance 

 compared with the next genus, 

 Rhombus, which contains the turbot 

 and the brill. The turbot, R. maximns, has no scales ; their 

 place is taken by tubercles. The brill, R. lavis, has no tubercles, 

 but small scales, which in shape are " cycloid," that is to say, have 

 no comb-like serrations at the rear edge, and are concentrically 

 striated, in much the same way as those in the illustration (Fig. 7), 



6. 



Fig. 7. CYCLOID SCALES. 



