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The simplest form perhaps belongs to the plaice (Platessa vulgaris) 

 ■whicli nearly approaches that of an oral, but the usual straight side 

 causes the lo-n'er end to be the smaller, whilst there is near the top, a small 

 projection. The concentric lines of growth in the otoliths of the flat-lishes 

 are readily discernible, and certainly make the bones somewhat shell-like, 

 so as rather to resemble the operculum of a gasteropod, for instance, the 

 horny brittle covering, with which a periwinkle upon withdi'awing itself 

 into its shell, closes the aperture. Like tlie already-mentioned examples, 

 this otolith is minutely toothed, or sciilptured around the margin. 



The oval form of the otolith of the brill {Ehomhus vulgaris) is broken 

 by the top being much flattened and indented, the centre may almost be 

 considered a notch, both sides are rounder than usual, but the symmetiy 

 is spoiled by the bend inwards on one side near the small end. 



The otolith of a small turbot is a very beautiful object. It has but 

 a sliglit resemblance to that of the brill, the larger end having the 

 indentation much larger and wider, the underside the straighter for some 

 little way, then it abruptly turns first down and then upwards, thus 

 making a sharp tooth. The scalloping of the edges is continued all round, 

 and well marked, which gives the bone a delicate shell-like appearance. 

 In an old fish the sculpturing is wanting, except upon the rounded side, 

 the indentation at the larger end becomes a notch, and the straight side 

 is so sharply cut off at an angle to the end of otolith, that the tooth is 

 scarcely seen. This veiy peculiar arrangement is so suggestive of a 

 portion having been broken off, that I threw several specimens away 

 before satisfying myself that I had not injured them in the extraction. 



All these otoliths agr^^e with one another in the respective fishes, 

 that is, there is no perceptible difference between the corresponding bones 

 of any one fish, but it is not so with those of the holibut {Hippoglossus.) 

 In this fish there is a marked variation. The otoliths are small for the 

 size of the fish. Those obtained from a head eight inches long, with an 

 internal skull of five and a half inches, measured only six lines, or about 

 the size of those of a medium brill. They are thicker in the middle tlian 

 the sides, and this is further reduced in the centre of the lower side and 

 each end, by a groove as it were gouged outwards from the middle. 

 That on the left is wing-shaped, but not so decidedly so as is the otolith 

 of the turbot, the depression at the larger, or posterior end, not so deep, 

 but the upper side of it rises considerably beyond the other whence its 

 outline makes an obtuse angle to the smaller end. The lower side does 

 not rise abruptly, forming a tooth as in the turbot, but curves in two 

 equal bends to the apex On the outside, the depression for the attach- 

 ment of the nerves is broad and deep.^ Tlie right otolith much more favors 

 that of the plaice in shape, but the notch at the end has a projection in 

 the centre, which, without filling it up entirely, sufficiently protrudes to 

 make the end of the bone look rounded instead of indented. This otolith 

 is flatter, and less wrinkled than the other, and the edges more regularly 

 carved from end to end. An examination of several examples of this 



