SENSE ORGANS OF AMIURUS. 257 
generally conical in form. The palisade cells radiate from the papille 
just as they do from the corium itself, and the result is that where the 
papillz are frequent, the interpapillary epidermal cells look as if 
arranged in pockets between them. (Fig. 2). 
(6) 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 eiements 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 papille of the corium are few 
and scattered, and the clavate cells are generally only ina single layer. 
In the latter the papille 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 
