802 Proceedings of Royal Society of Edinburgh. [ sess. 
gatherings, was first noticed in a deep-water sample from Upper 
Loch Fyne. 
Thaumaleus rigidus and Monstrilla longicornis (45 and 46) 
belong to a somewhat remarkable group of Copepoda, and were first 
made known to science by the late Mr I. C. Thompson of Liver- 
pool. The life history of the species belonging to this group does 
not yet appear to be very well known, but it is generally con- 
sidered that they are parasitic—at least, at some stage of their life. 
The first of the two species mentioned here was observed only 
twice, and the other once during the whole year. 
The next two species, 47 and 48, belong to a family on which 
an interesting and elaborate monograph has been published by 
Dr Giesbrecht of Naples. Nearly all the members of this family 
appear to live as commensals with other organisms, several being 
found living in the water passages of various sponges. The two 
mentioned in the table were only noticed in samples collected in 
December. They appear to live about the roots of sea-weeds. 
Caligus rapax (49) was noticed on two occasions, once in October 
and once in November. It is the only species of a group of fish 
parasites which adopts, to a large extent, the free-swimming habits 
of the pelagic Copepoda ; and though numerous examples may be 
found running over the skin of large Gadoids, the species is also of 
frequent occurrence in tow-net gatherings collected in the open sea. 
REMARKS ON THE SPECIES ENUMERATED IN TABLE III. 
In the preceding notes, the Copepoda only are referred to, but, 
as previously stated, species belonging to various other groups of 
Crustacea were also observed; these are recorded in Table III. 
They were, however, with a few exceptions, very seldom noticed, 
and chiefly towards the end of the year. Four species of Cladocera, 
viz., Hvadne Nordmanm and Podon polyphemoides, intermedius, and 
Leuckarti were moderately frequent, so also were some larval and 
young forms. The first two species occurred more commonly in 
July, August, and September, while the third was more frequent 
in the latter month than at any other time during the year. 
Podon Leuckarti, on the other hand, occurred sparingly from March 
till near the end of July. Larval Balani were, with one or two 
