94 DR. W. C. MSINTOSH ON THE HAIRS OF CARCINUS MJENAS. 
front, short, truncated, and then perfect hairs become plentiful. This membranous por- 
tion is apt to bend under the harder part when placed beneath the microscope, and thus to 
escape observation. In structure the hairs last mentioned are very beautiful; they are 
simple, delicate, have a bluish opalescence in the water, and taper to a fine point. A little 
granular marking of the central portion, at the base and for a short way up, breaks the 
sameness of structure; and along their exterior, for fully the terminal half, are slight 
serrations, best marked in the soft Crab, or in hairs subjected to nitric acid. In the 
perfect or hard state of the Crab it was noticed that numerous granules and cells always 
clung to the hairs, which led to a more minute examination for the fine serrations. 
These rough points in the hairs may detain certain minute alimentary matters in the 
stomach, which would otherwise have escaped between smooth hair-fibres without impe- 
diment. The basement-membrane is for the most part granular, with an occasional faint 
. cellular or areolar marking. 
In the neighbourhood and attached to the base of the small tooth at a, fig. 12, which 
represents the inner aspect of the superior wall of the stomach, a little to the outside of 
the posterior termination of each horny ridge, there are many hairs 
of delicate structure, similar to those mentioned previously. On 
the membrane are found many minute cells and granules, some of 
the former like those already described, but generally much smaller. 
A portion from the upper wall, enclosed in dotted lines, and marked 
b, presented the following aspect :—All the membrane anterior to 
the little black tooth, c, was quite uncovered by hairs, its surface 
being only varied by wrinkles, cells, and granules. The hairs com- 
mence a little behind this tooth, at first short and sparse, then 
longer and in greater numbers, although at no part are they very 
closely placed; on. the outer side they scatter and soon disappear. 
The surface of the central horny piece, d, is for the most part smooth throughout, only — 
a few of the ordinary hairs appearing at itssides. On the inner sides of the great lateral 
teeth, e e, the hairs are of like aspect and structure. 
An incision, represented by the dotted line’ f, running up the mesial line, divides 
what remains behind the long horny centre piece into two halves. From before back- 
wards the surface of each is roughened and hardened by numerous calcareo-horny 
masses. Anteriorly, the usual hairs surround the bases of the latter, while the trans- 
lucent portions are left bare. The first that occur in the mesial line anteriorly are long 
and rather closely set; and the general surface of the cavity is studded, sometimes with 
stronger bristles on the horny portions, as before, sometimes with more delicate hairs on 
the translucent parts, which are bare in front. "Towards the posterior edge they become 
slenderer and finally shorter (Pl. XX. fig. 7). Near the mesial line, however, posteriorly, 
some long hairs are found over a considerable area, and placed mostly in one direction 
in the neighbourhood of a dark horny mass ; their structure is the same as that formerly 
described. The greater part of the membrane is dotted over with distinct granules, 
which in some places merit the name of cells. In this region some of the hairs arise in 
a peculiar manner, so as to be grouped in companies of three or four (Pl. XX. fig. 10). 
» Fig. 12. 
