DR. W. C. M'INTOSH ON THE HAIRS OF CARCINUS MJENAS. 91. 
the inner angle they rise into a longer tuft. Few or none are found in the second limb. 
On the outer crest of the same structure in the third, fourth, and fifth limbs there is a 
row of bristled hairs. The éschiopodite has chiefly branched hairs on its inner margin, 
some of the shorter ones being serrated at the tip, and with their lateral spikes scanty 
and short. Near the inner margin is a row of short serrated hairs which does not quite 
reach the anterior part of the segment. On the external margin these are feathered 
only. The third limb has a line of long hairs, like the basipodite of the same extremity. 
On the convex margin of the fourth limb there is a crest of branched hairs for two-fifths 
of its basal length. Along the same margin (outer) of the fifth, at the base, is a ridge, 
first of shorter, then of longer branched hairs. The meropodite is three-sided, with one 
angle below; the two upper angles are covered (the outer mostly at the base) with 
branched hairs, some of which have serrated tips. The fifth has a row on its outer 
margin extending a little more than halfway forward, short at first, longer towards its 
distal extremity. On the cerpopodite a series of branched hairs occurs along the upper 
margin of the joint between this and the propodite, beneath the formidable spike which 
overhangs the hollow. In the second limb this segment is provided with a powerful and 
thickly-set row on its inner margin for about four-fifths of its extent; and, in the soft 
Crab, with a series of short hairs in the outer dorsal groove. In structure these hairs are 
peculiar, being sparsely bristled for their first half, often on one side only, but thickly 
coated with short sete throughout the rest of their extent. On the third limb there 
are some minute brushed hairs in the groove on the upper and outer surface, and on its 
inner edge and other portions a few more, sometimes in pits. The outer margin of the 
fifth has a complete mane of hairs, chiefly of the brushed variety, only a few being 
branched. The two terminal segments of the chelæ (dactylopodite and propodite) are 
supplied with a number of small tufts, which stud the pits in the grooves which stretch 
the entire length of the former and the opposite part of the propodite; they are short 
and slightly serrated at the tips. Where the last-mentioned segment gives joint to the 
former are some finely feathered tufts, best seen in the soft Crab. The hairs of the 
propodite in the second and third limbs more or less resemble in situation and struc- 
ture those on the carpopodite of the corresponding limbs. The fourth possesses a short 
row of brushed hairs on its inner groove at the base, while the outer groove on its 
upper surface has a row of similar hairs halfway down from its proximal end, On the 
outer margin of the fifth is a row, chiefly of brushed hairs, except at the base, extending 
nearly to the tip. It will be observed that the hairs differ in a regular manner from one 
segment to another along the outer margin of these parts. The basal portion of this 
limb has branched hairs; but they alter their character towards the tip, and assume 
most markedly the brushed form. 
With regard to the branched hairs in general, transverse markings are readily observed 
in many of those described, joining as it were the roots of two opposite secondaries. 
Each of the latter marks its origin from the parent trunk by indenting it with a little 
circular depression, which is usually conspicuous enough. Parasitic growths of very 
various forms abound on the hairs of the limbs, often to such an extent as to darken the 
entire field of the microscope. , 
