88 DR. W. C. M'INTOSH ON THE HAIRS OF CARCINUS MANAS. 
. Fifth pair of Foot.jaws.—At the extremity of the innermost organ, a, fig. 6, are a 
series of strong smooth hairs, towards one end of which one or two more slender and 
elongated hairs, slightly serrated in the soft Crab, project conspicuously beyond the 
others, all the more so as they are placed next a margin (posterior) devoid of hairs. 
Towards the convex margin there are a number of very powerful bristles, short, smooth, 
and having the peculiar marking about midway previously noticed. Springing from the 
cuticle by a broad base, the hair for fully a third of its length tapers very little, so as to 
appear nearly cylindrical; this basal portion ends by a transverse marking, and is 
distinct from the terminal by the change in appearance and arrangement. The 
external chitinous investment is meagre, and it seems almost entirely composed 
of the cellulo-granular central portion. At the termination of this part there is a 
distinct narrowing of the entire breadth of the hair, yet the external portion becomes 
essentially thicker than before on each side by encroaching on the central space, which 
now rapidly narrows to a fine extremity, and terminates only with the end of the hair. 
The structure of this central portion seems to be the same as the basal, only it is less 
distinct and yellower, from the thicker nature of the investing chitine (vide Pl. XIX. 
fig. 12). Along the curved margin of the limb are many long serrated hairs, while on 
the concave side there are few. Some short, serrate and smooth hairs also occur on 
the general surface. 
The limb, û, has its broad extremity covered with stout, smooth spikes, of somewhat 
similar structure to those of the foregoing portion, but shorter. When acted upon by 
acid, some of the smaller hairs appear to have three portions; 
the central tunnel containing a granular structure, then on each 
side a pale border in the smaller (darker in the larger, where it is 
still indicated), and, lastly, the cortical. The latter is always بك‎ 
marked in these hairs by longitudinal lines, which give it a 
fibrous aspect and a structure akin to that of the shell. Close 
by these bristles are a number of smaller serrated ones, which cover 
base and for some distance on the limb below. The inner corner ( just where the dotted 
line comes off) has some longer and slenderer serrated hairs, which come up from the 
oral side and rise to a level with the preceding; altogether the arrangement has a very 
pectinate aspect. Along the oral margin there are some long serrated hairs, but none 
on the outer. 
The third limb of this foot-jaw, c, has the following hairs:—At the tip there is often 
found, in the complete state of the Crab, a dense black mass, caused by the total conceal- 
ment of the hairs in extraneous growths. In the soft and clean Crab there exist on the 
angle at the tip, and quite separated from all others, two long and peculiarly serrated 
hairs, which jut from the corner like tusks. The serrations in these hairs are interesting, 
and may with propriety be termed minute teeth. A little beyond the middle of the hair 
these blunt teeth commence, following each other to the number of eleven or twelve on 
Nes. berum - Ses intervals. The terminal fifth of the hair is quite free from 
ييه‎ MR 0 s g. AL): At the rounded margin opposite this, and along the 
" me finely bristled or branched hairs, one or two with serrate tips. 
Fig. 6. 
