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Show 1894.] TELEOSTEAN MORPHOLOGY. 441 Plaice rebut such a supposition, while no evidence is forthcoming in its favour. The same authority has also failed to detect any difference in the habits of partially ambicolorate but structurally normal fish. Plaice and Flounders, more or less coloured on the underside, are extremely common in the Humber, and having kept a considerable number of such fish in the Cleethorpes tanks and watched their behaviour attentively, m y own experience is precisely to the same effect as Cunningham's. The young Brill, with the hooked dorsal, structurally abnormal but not ambicolorate, differed in its habits in no respect from several normal Brill of about the same size, taken at the same place, and kept in the same tank. Of the habits of the Sole under discussion I have of course no knowledge, the fact that it was trawled in company with a number of normal examples being of little value, since I have occasionally trawled such essentially pelagic fish as Mackerel and Herrings. The complete asymmetry of everything but the eyes seems, however, to refute the idea that it could possibly have maintained a vertical position, and the complete absence of pigment from the blind side of the head and trunk would seem, in the light of Cunningham's investigations, to show that that side could not have been exposed to the light, unless the susceptibility of the individual were so slight that the power of pigment-production was practically lost by the derma of that side. The bearing that the condition of our specimen has upon the question of ambicoloration, into which I have entered at so great a length above, appears to m e to be this,-that the phenomenon of complete ambicoloration, as typified by some Cyclopean Pleuronectids, cannot be held to depend on the mere arrest of the migration of the eye, unaccompanied by other structural abnormality \ The proposition, as laid down by Cunningham and MacMunn, that complete ambicoloration occurs only in Cyclopean examples, is in no way affected thereby, but, as it seems reasonable to suppose that any abnormality of habit (whether in the pelagic or later stages), such as Giard 2 considers to exist in Cyclopean Turbot, would surely be intensified in a specimen like that now before us, I should say that the theory of the French observer m ay be considered to be finally disposed of. Anatomical Features. Most of my superficial and all my subdermal observations were made after the specimen had been some months in alcohol. O n removing the skin from the right (normally the ocular) side 1 That ambicoloration may exist in a specimen not essentially differing in external characteristics from the Sole now under consideration is shown by a young Turbot in the St. Andrews Museum, described and figured in the 'Fauna of St. Andrews Bay' by Professor Mcintosh. The specimen is only a few inches in length and normally developed, except that the eyes are on different sides of the head, and pigment exists on both sides of the body. 2 " Sur la Persistance partielle de la Symetrie bilaterale chez un Turbot," C. R. Soc. Biol. Jan. 22, 1892, p. 31, and Nat. Sci. i. 5, p. 358. |