OP ARTS AND SCIENCES. 7 



control the motion of the eyeball in the young Flounder maintain also 

 a very powerful strain upon the frontal bone while still cartilaginous 

 and readily flexible, and no doubt help to twist it in accordance with 

 the gradual change in the position of the eyes. 



While the observations of Malm on the young stages of Flounders 

 tended to show the improbability of the eye passing through the skull 

 from the blind side to the binocular, the observations of Steenstrup on 

 the genus Plagusia, seemed, for that genus, at any rate, to show clearly 

 that the eye did pass through the tissues of the head, during its transfer 

 from the blind to the binocular side. But neither Malm nor Steenstrup, 

 nor subsequently Schiodte, actually traced the changes undergone dur- 

 ing the process. Steenstrup's specimens were alcoholic ; and, although 

 his theory was substantiated by observations on a number of in- 

 termediate stages of the passage of the eye through the tissue, yet, 

 on the other hand, the observations of Malm, making it probable 

 that the eye merely went round the head, in a manner not yet 

 explained, were equally precise. I had myself traced quite a number 

 of Flounders, in all of which the eye was transferred in accordance 

 with the process described in the commencement of this paper, and 

 figured on Pis. III.-VIIL, — a process completely in accordance with 

 the suppositions of Malm, and in direct contradiction to the theory of 

 Steenstrup. In the late summer of 1875, however, I traced to my 

 satisfaction the development of a very transparent Flounder (PI. X. 

 fig. 1), — so transparent, indeed, as to rival the most watery of Jelly 

 Fishes. When placed in a flat glass dish, it could only be distinguished 

 by allowing the light to strike it in certain directions : otherwise, all 

 that was visible were the two apparently disembodied bright emerald 

 eyes, moving more or less actively. 



In this Flounder (PL X. fig. 1), already of a considerable size, — 

 over an inch in length, — the position of the eyes was perfectly sym- 

 metrical. They were placed also at considerable distance from the 

 anterior extremity of the snout ; so that, judging from the size of the 

 fish and the position of the eyes, as well as from the extension of the 

 dorsal almost to the nostrils, I inferred that I had a new Flounder, in 

 which the eyes would probably always remain more or less symmetri- 

 cal, and in which the transfer of the eye from one side to the other 

 was replaced by the exceeding transparency of the body, allowing 

 either eye, owing to the great range of motion of the eyes both in 

 a vertical and horizontal direction, — a feature characteristic of all 

 Flounders, — to be really useful on both sides of the body. A 

 Flounder can move his pupil vertically and horizontally through an 



