620 NOTES AND MEMORANDA. 



There are two conspicuous black bands across the caudal region, three 

 smaller ones on the lower half of the body only alternating with the 

 other two, and a black patch at the root of the tail. Black chromato- 

 phores are scattered over the peritoneum posteriorly, along the ventral 

 interspinous bones, and along the lower margin of the abdomen ; a 

 few black spots are present also on the clavicle. On the head, a line 

 of black chromatophores marks off the posterior margin of the large 

 optic lobes ; the mandible is also pigmented, but not so deeply, and an 

 irregular double row extends longitudinally along the inner surface 

 of the gill cover. The eyes are of an intense black, and are notched 

 in front (Fig. 2). 



The most striking features of the post-larvse, in addition to their 

 length and relative thinness, are the long head, the projecting snout, 

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

 the early stage of metamorphosis. The left eye has not yet begun 

 its migration. Of all the pleuronectid larvae yet described, it is 

 undoubtedly the latest and largest at this stage. In these striking 

 features they are very like the long-rough dab.* The distribution 

 of pigment is about the same ; the large mandible and depression 

 behind the snout are alike in both. They differ, however, from the 

 long-rough dab in having a more elongated body at the stage of 

 metamorphosis mentioned, and in having a greater number of fin- 

 rays in the medium fins. Perfect accuracy was impossible in the 

 counting of the latter, because the embryonic condition still persisted 

 at the anterior and posterior ends, but the numbers were approximately 

 D, 103 to 105 ; A, 83 to 85. These are beyond the formulae for the 

 long-rough dab, but are within those for the halibut, as given by 

 Smitt ;"!• they are also within those for the pole-dab (P. cynoglossiis), 

 and herein lies the ditliculty. The latest stage, described by Holt, has 

 a similar distribution of pigment, with the exception of the absence 

 of chromatophores along the ventral aspect ; these may, of course, 

 develop later. Holt's specimen was less than 6 mm. in length ; but 

 their absence is of some importance, because they are present even 

 in the earliest stage of the long-rough dab, to which the halibut is 

 more nearly allied. In Holt's specimen the notochord is not yet bent 

 up, and the other post-larval characteristics have not appeared. As 

 regards form, internal structure, and structure of the head, these 

 species are too closely allied to show distinctive characteristics at such 

 early stages. The size of the mouth might be thought of as a guide, 

 because the long-rough dab and halibut have a large mouth and the 

 pole-dab a small one, and in this respect the present specimens are 



* Ann, Rep. Scottish Fishery Board, xvi., for 1897, pjj. 235, 236, Figs. 17-26. 

 t Scandinavian Fishes, part i., p. 409. 



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