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



more than 45 fathoms, while no less than 63 occurred below the 100 fathom line, 

 viz. 8 at 220, 47 at 154, and 9 between 115 and 127 fathoms. We have also 

 evidence that the parents spawn and that the yomig are reared at considerable 

 depths, since ripe females were taken exclusively at 153, 154, and 220 fathoms,* 

 while the very young examples were most abundant between 70 and 80 fathoms — 

 the greatest depth at which it was possible to work a fine-meshed net suitable for 

 their capture. 



The species has been described with sufficient accuracy by Day, but it may be 

 remarked that the specimen from which he seems to have taken both his diagnosis 

 and his drawing must have been slightly abnormal in so far as concerns the curved 

 portion of the lateral line. This is described, and illustrated, as "almost semi- 

 circular," whereas an almost rectangular condition is usual. Variation in the 

 curve, however, occurs no doubt in this, as in other species of the genus, f and we 

 are far from impugning the accuracy of the author's representation of the 

 specimen in question. 



The differences in colouration to which Day refers, and which are 

 illustrated by Couch in his drawings of the "Carter" and " Sailfluke," appear 

 to be due to the environment of the individual rather than to the existence 

 of variety in pigmentation. Thus specimens obtained during the Survey 

 from deep, or moderately deep, water, exhibited an uniform pale and 

 slightly pinkish fawn-colour on the ocular side, varied, if at all, only with very 

 faint greyish markings of indistinct outline. Such a colouration is reproduced, 

 though somewhat unsuccessfully, in Couch's figure of the "Sailfluke." On the 

 other hand, the dark ring-like markings shown in the figure of the " Carter" were 

 only noticed in specimens from shallow water — most conspicuously in one taken 

 at 4 to 5 fathoms in Loughrosmore Bay. Though no opportunity of testing the 

 matter occurred, it may be safely predicted that such markings might be greatly 

 modified, if not entirely obliterated, by exposing the specimen to different 

 conditions of light, etc., as has been already done in the case of Solea vulgaris by 

 Cunningham. J It is less probable that markings of similar intensity could be 

 produced on uniformly coloured examples from deep water, at all events with the 

 same rapidity, since, in the light of the more recent experiments of the same 

 author, § we are tempted to infer that the absence or insufficiency of light may 

 affect the ocular as well as the blind side of the body, and that the dark 

 cliromatophores, to the expansion of which the ring-like markings are due, may 

 fail to develop to the same extent as in shallow- water specimens. 



* No ripe male was taken at less than 38 fattoms. 



f It is frequent in R. maximus. 



X "Treaties on the Common Sole," p. 110, "Mar. Biol. Assoc," Plymouth, 1890. 



§ "Zool. Anzeiger," 1891 ; or " Journ. Mar. Biol. Assoc," vol. iii., No. 1, p. 111. 



