270 NATURE NOTES. 
body tightly pressed to the roots of the weed. The male is 
a fine bright red colour, and has the left chele curiously 
twisted and lined with dense pubescent hair. When 
alarmed, this species, in spite of its crab-like appearance, is 
capable of using the tail in awkward swimming movements. 
When swimming, the little creature has a very curious 
aspect, for the heavy great claws seem to overbalance the 
body, and after the first few strokes the animal falls over 
and swims back downwards. It seems to be greatly relished 
as food by the larger Crustacea. Our other species, P. 
platycheles, is very different in appearance, and seems always 
to occur in muddy places. I have never seen it attempt to 
swim, though, like the smaller species, it uses the tail when 
attempting to regain the normal position after having been 
turned on the back. It is quite common, but is very apt 
to be overlooked on account of the dingy colour, and the 
habit of cowering down when exposed by the overturning of 
the stone under which it has been lurking. The dense 
fringe of hairs on the chelipeds, which is almost always 
filled with mud particles, and the muddy hairs on the back, 
cause the crab to resemble a flat pebble attached to the 
stone by tenacious mud. 
An interesting peculiarity of the Forth area is the extra- 
ordinary abundance of the common hermit crab (Pagurus 
bernhardus), the shells containing the hermits being in the 
majority of cases covered by a dense growth of the zoophyte 
Hydractinia echinata. At Alnmouth—a not very distant 
locality—the association of hermit and zoophyte seems at 
most to be rare, while at Longniddry it is exceedingly com- 
mon among the hermits which swarm in the pools. 
The interesting Masked Crab (Corystes cassivelaunus) would 
appear to be common along the sandy beaches in the vicinity 
of Gullane and Aberlady; the dried shells are certainly not 
infrequent along the shore. The only Spider-crab which 
can be called common is Hyas araneus, very abundant in 
the Laminarian zone and among the finer kinds of weed. In 
muddy places I have found small specimens which in the 
size of their post-orbital process approach H. coarctatus, a 
species whose distinctness is denied by some authorities. 
The occurrence of H. araneus in great abundance is a 
