of the Fishery Board for Scotland. 271 



is now orange by transmitted light, except in the median fin, where it is 

 brown " (Holt . 



Previous to the publication of the paper just referred to, Petersen* had 

 described a post-larval pleuronectid measuring 32mm. in length. He 

 considered it to be a Halibut {Hippoglossus vulgaris). Kylef and Holt and 

 ByrneJ have recently described post-larval stages of the witch, and these 

 agree closely with Petersen's form, which is apparently really a witch. 

 It has, moreover, the spinous armature of the operculum to which Holt and 

 Byrne draw special attention. § The fin-ray formulae for these specimens 

 were as follows: — Petersen's — Dorsal, w, 104; Anal, 88 ; Caudal, 82. 

 Kyle's specimens (two in number) — Dorsal, 103 (105); Anal, 83, 85; 

 Caudal, 18. Holt and Bryne— Dorsal, 108 ; Anal, 95. 



The post-larval witch is a characteristic form which cannot be con- 

 founded with any other known species. Its main characters are its long and 

 narrow post-anal body ; the well-marked triple-bar arrangement of pigment 

 on the same ; the prominent head and snout, and its extended transforma- 

 tion period. Kyle in this connection says, in referring to the two examples, 

 12 and 14mm. long respectively, described by him, that their "most striking 

 features, in addition to their length and relative thinness, are the long head, 

 the projecting snout, with the deep depression over the eyes, and the 

 early stage of metamorphosis." In Dr. Fulton's collection the largest 

 post-larval {i.e. pelagic) witch measures 40mm., while the smallest young 

 witch {i.e. transformed) measures 44mm. Holt describes one of the 

 latter which measured 42mm. 



The only other pleuronectid of our waters which approaches the witch 

 in having a lengthy post-larval period is the Lemon Sole {Pleuronedes 

 microcephalics). Post-larvse of this form have been found measuring 

 27mm. (Holt), but the general shape of the pelagic stages of this species 

 Is very different from that of the witch ; the outline of the former is oval, 

 whereas that of the latter is elongated. 



The witches from which the drawings were made exhibited black pig- 

 ment only. The pigment other than black has disappeared since they 

 were preserved; and in some cases the black pigment has faded consider- 

 ably. This probably accounts for the fact that some variation on the 

 pigmentation is found in the forms described, especially as regards the 

 marginal fin. The outer edge of the marginal fin was, moreover, some- 

 times frayed, and in consequence the presence of pigment there was not in 

 these cases determined. 



It is hoped that the sketches here supplied will aid in the diagnosis of 

 preserved examples. A number of the drawings are of natural size ; the 

 majority are enlarged. It is sufficient to note that the post-larval char- 

 acters are constant ; the general form, which is more readily indicated by 

 the sketches than by a word-picture, is, when taken along with the bar 

 arrangement, sufficient to indicate the species. A brief note will be 

 given of each of the stages illustrated. 



The first (Fig. la) is an early post-larval example, measuring in total 

 length 5 ■2mm., in greatest breadth "TSmm. It has the typical pleuronectid 

 form, viz. a short abdomen and a long post-anal region. The marginal 

 fin shows no trace of fin-rays ; the caudal fin is still diphycercal. The 

 pigment is well marked. At the point of the mandible there are a few 

 black pigment spots, and in the pectoral region there is a ventral group 

 of spots. On the hind dorsal area of the abdomen a group of large 

 chroraatophores is visible, and along the keel of the abdomen there is a 



* Report of the Danish Biological Station, iv., 1893. 



•\ Journal of tlte Marine Biological Association, vol. vi., No. 4, Dec. 1903. 



+ Report on the Sea and Inland Fisheries of Ireland, 1901, Pt. II., Dublin, 1903. 



§ Dr. Petersen has informed me that he is satisfied that the form is a witch. 



