EXPLANATION OF PLATE ONE. 



[All the figures on this plate are from original drawings by Prof. J. Wyman.] 



FIG. 1. Brain, nerves and organ of hearing of Amblyopsis spelaus; enlarged; a, olfac 

 tory lobes and nerves; 6, cerebral lobes; c, optic lobes; d, cerebellum; , 

 organ of hearing, showing the semicircular canals, with the otolite repre- 

 sented in place by the dotted lines; /, medulla oblongata; g, optic nerves 

 and eye specks. 



FIG. 2. Otolite, enlarged. 



FIG. 3. Eye, magnified (natural size one-sixteenth of an inch in length) ; a, optic nerve ; 

 6, sclerotic membrane ; c, layer of colorless cells ; d, layer of pigment cells 

 (iris?); e, lens. 



FIG. 4. Lens, enlarged and showing the cells. 



FIG. 5. Eye, enlarged, showing the muscular bands, a, a, a, a; b, the lens pressed out 

 of place; c, the optic nerve. 



FIG. 6. Top of head, showing the canals under the skin, of the natural size. The two 

 black dots and lines indicate the eyes and optic nerves in position. 



FIG. 7. Top of head, showing the arrangement of the ridges of papillae. Natural size. 

 FIG. 8. One of the ridges of papilla? fr*om the head, magnified. 



FIG. 9. Three of the papilla? from the ridge, still more magnified, showing the cup- 

 shaped summit and projecting filament. 



FIG. 10. A portion of the ridge magnified, and treated with acid, to show the arrange- 

 ment of the nervous plexus supplying the papillae with nerve filaments from 

 a branch (a) of the fifth pair. 



FIG. 11. Epithelial cells from the head. 

 FIG. 12. Epithelial cells from the body. 

 FIG. 13. A fish with eyes, found in the stomach of an Amblyopsis. 



(53) 



