SENSE ORGANS OF AMIURUS. 257 



generally conical in form. The palisade cells radiate from the papillae 

 just as they do from the corium itself, and the result is that where the 

 papillae are frequent, the interpapillary epidermal cells look as if 

 arranged in pockets between them. (Fig. 2). 



{b) The stratified fibrous layer exhibits the disposition so well 

 known in other osseous fishes — strong parallel bundles penetrated at 

 intervals by vertical fibres. 



(c) Beneath the above is the adipose layer, which differs conspicu- 

 ously both in thickness and in the character of the tissue in various 

 regions, a difference chiefly due to the mode of arrangement of the 

 fat therein. The adipose layer is separated from the underlying 

 muscles by a membrane formed of bundles chiefly parallel to the 

 surface of the skin. 



THE CHARACTER OF THE SKIN IN DIFFERENT REGIONS. 



Apart from the modifications induced by the presence of the cut- 

 aneous sense-organs, the skin exhibits characteristic peculiarities in 

 different regions. Thus, on the lips the clavate cells are absent, and 

 the mucus-cells also few in number, the ordinary epidermal cells 

 making up the rather exceptional thickness of the epidermis in this 

 region. It is, perhaps, owing to the great numbers of sense-organs 

 that these peculiar elements of the epidermis are absent, because 

 elsewhere, in the immediate neighbourhood of sense-organs, the same 

 peculiarity is noticeable. 



The fibrous layer of the corium in the head is generally much 

 thinner than that on the trunk ; On the other hand, the subjacent 

 adipose layer is thicker in the former than in the latter region. The 

 epidermis is somewhat thicker on the sides of the head than on the 

 upper and lower surfaces, while on the trunk the reverse obtains. This 

 is apparently due to a greater number of clavate cells in both cases. 

 Again, in the neighbourhood of the vent and urogenital papilla, the 

 clavate cells are absent, or, at any rate, very sparingly represented. 



Important points of difference between the skin on the lateral region 

 of the trunk and that of the head may be gathered from a comparison 

 of Figs. 1 and 2. In the former region the papillae of the corium are few 

 and scattered, and the clavate cells are generally only in a single layer. 

 In the latter the papillae are so frequent that the epidermis looks on 

 section as if it were arranged in pockets between them. There the 

 clavate cells are in several layers, and they adapt themselves to the 



