IO _ Distribution of the Smaller C rustacea. [Sess. 
is furnished with two divergent barbs, one on each side of 
the head, so that the head cannot be removed without dissect- 
ing the eye. The presence of the parasite probably causes 
the eye to become blind. In illustration of this, on one occa- 
sion my son tried to catch a sprat—one of a number which had 
made their way into one of the Leith Docks. This particular 
sprat had a parasite on one of its eyes, and its would-be captor 
managed to get his hand almost within touch of the fish on— 
that side on which the parasite was attached, apparently 
without being noticed, and was about to grasp it, when it 
turned round, and, seeing him, made off like a flash of 
lightning. . 
Nicothoé astaci furnishes a most interesting example of 
limited distribution. This copepod, so frequent on the gills 
of the common lobster, is apparently found nowhere else, at 
least in its adult stage; and it is somewhat strange that, 
though the parasite is so frequent, there are so few published 
records of its occurrence. Indeed, I know of no Scottish 
records of Micothoé except those I have myself published. I 
seldom fail to find the parasite on lobsters that have not cast 
their shells for some time previously. Though comparatively 
a small species, this parasite is of interest from the two great 
wing-like lateral expansions of the posterior part of the 
thorax. These expansions appear to be the result of an 
extraordinary development of the fourth thoracic segment. 
The ovisacs are also large, and, with the lateral expansions, 
give to the species, which otherwise is not unlike some of our 
common Harpactids, an appearance unusual among copepods. 
Adult specimens of the parasite are extremely inactive, and if 
removed from the lobster’s gills and placed in sea-water, they 
make no apparent effort to change their position. The only 
evidences that they are alive are the peristaltic movement of 
the intestine and the persistence of their semi-transparent pink- 
ish colour. Speaking of their sluggishness, Milne-Edwards 
—quoted by Dr Baird—states that they allowed themselves 
to be torn to pieces without making the least movement or 
quitting their hold. But they also seem to be tenacious of 
life, for my son removed several specimens from a lobster’s 
gills and placed them in sea-water, where they continued to 
live for at least five weeks. 
