378 Prof. J. C. Schiodte on the Development of 



Fig. 4. Section of the upper portion of the tooth of PolypteruSj from 

 Ag-assiz, showing the cap of enamel, a. 



Fig. 5. Section of portion of maxilla oi Wiizodopsis, much enlarged, ex- 

 hibiting the bony pillars supporting- the teeth : a a, bony pillars ; 

 b, b, teeth in an abraded condition, the enamel having all disap- 

 peared, and, in some instances, portions of the dentine. 



XL VI. — On the Development of the Position of the Eyes in 

 Pleuronectidge. By Prof. J. C. ScHioDTE. Communi- 

 cated by C. A. Gosch, Esq. 



[The question of the asymmetry of Plem-onectidge lias of late 

 attracted so much attention, and we possess so few reliable 

 descriptions of the appearances presented by very young spe- 

 cimens (whereby alone that question can be solved), that the 

 following observations on this subject by Prof. Schiodte will 

 doubtless be found highly interesting, not only to ichthyolo- 

 gists, but to zoologists generally. I wish particularly to di-aw 

 attention to two of his results, now established by actual exa- 

 mination of successive stages of development of the same spe- 

 cies, viz. :^— first, that the eye of the blind side glides across the 

 head in front of the dorsal fin without ever disappearing from 

 view, and, when arrived on the other side of the dorsal fin and 

 clear of it, recedes backward alongside the fin, which does not, 

 as supposed by some, prolong itself after the passage of the eye ; 

 and, secondly, that this shifting of place is a very slow process, 

 for which, in all probability, preparation is made in the foetus. 

 Prof. Schiodte's article is destined shortly to appear in the 

 fifth volume of the ' Naturhistorisk Tidsskrift ;' but having 

 been favoured by the author with a separate impression, I am 

 enabled already to present it to the readers of the ' Annals.' 

 The author begins by describing the specimens which form 

 the principal material of his treatise in the following manner.] 



On examining a young specimen of Bhojnbus barbatus which 

 lies before me, and which measures 18 millims. in length 

 from the apex of the closed lower jaw to the extreme end of 

 the caudal fin, I observe that the ramifications of the mucipa- 

 rous canal on the head are not traceable; but the oiitline of the 

 parts of the mouth, of the prseoperculiim, and the opercula are 

 clearly perceptible through the skin, as well as the layers of 

 the muscles, particularly of the great masseter on the right 

 side. The left eye stands very nearly opposite to the middle of 

 the upper jawbone. The right eye is placed at the top of the 

 head, in front of the dorsal fin, but so much inclined to the 

 left, that only one-third of its surface is visible when the fish 



