258 American Quarterly Microscopical Journal. 



thickest in front, but very minute everywhere, rarely exceeding 

 .025'"™" in diameter, and are so thickly placed that I counted twenty- 

 five on a surface of the maxillary measuring but .5"""- in each di- 

 rection. They are destitute of pigment cells, which thickly star the 

 skin elsewhere. The surface is very slightly elevated over each 

 cluster, but no cilia or external processes of any sort could be 

 demonstrated. (On the barbel of the cat-fish, it should be noted 

 that these clusters form evident small tubercles.) When a piece 

 of the epidermis is detached from the corium, these bodies com- 

 monly remain imbedded in it, but can easily be picked out from 

 the under side, leaving circular openings in the epidermis. These 

 openings are, however, sometimes more or less completely covered 

 by a delicate, granular film (Fig. 6), which is probably only the 

 coagulated slime of the skin. When the clusters themselves are 

 examined they are seen to differ considerably in shape (Figs. 2-5), 

 but the outer end is always the smaller, as if the cells were crowded 

 more closely together at their distal extremities. 



Various methods of macerating these bodies were tried for sepa- 

 rating their cells, but, owing probably to the previous action of the 

 alcohol, without satisfactory results. Fragments of the epidermis 

 were usually stained with Beale's carmine and placed in clean 

 glycerin ; the sensory bodies were then picked out and trans- 

 ferred on a needle point to fresh glycerin, w^here they were care- 



DESCRIPTION OF PLATE XIX. 



Fig. I. Amia calva, L., young form. Showing distribution of sensory bodies. 



Fig. 2. One of the sensory bodies from the skin of the head ; the upper end is 

 the distal. Drawn with the eye-piece micrometer, and slightly idealized. 



Fig. 3. Same as 2, but accurately drawn with camera-lucida. Logwood stain- 

 ing, dammar mount. 



Figs. 4 and 5. Outlines of sensory bodies. Camera-lucida drawing. 



Fig. 6. Fragment of epidermis from which a cluster has been removed. Tlic 

 opening is partly covered by the granular film mentioned in the text. 



Fig. 7. Sheathing cells from the outer layer. 



Fig. 8. One of the outer cells of a cluster. 



Fig. 6. Group of the same. 



Figs. 10 and 11. Columnar cells of a cluster. 



Figs. 12, 13 and 15. ^ Modified columnar- cells. 



Fig. 14. Group of fusifonn cells, with a filamentous coUimnar cell. 



Figs. 16 and 18. Other intermediate forms. 



Figs. 17 and 19. Rod-cells. 



Fig. 20. Grou]5 of epidermal cells. 



Figs. 21, 22 and 23. Cells from deeper layer of epidermis. 



