AMPHTPODA AND ISOPODA OF THE FIRTH OF CLYDE. H 



worked from an oar-boat with as much success as 

 from a faster-going vessel, as great speed is rather 

 an objection when the water is made to rush into 

 the net more rapidly than the meshes can let it 

 out. For the surface work the best time seems to 

 be after sunset, and the darker the better. I am 

 not aware that any of these marine animals which 

 crowd the surface of the water at night are peculiar 

 to the surface. With few exceptions, all that have 

 come under my own observation in the surface-net 

 have also been taken by the dredge. Considering 

 the depth of bottom from which many of them 

 must have come, it is a question how (if ever) these 

 tiny forms get back through the strong currents 

 and tides to their wonted habitat. These nets 

 were used by the steam yacht Medusa with great 

 advantage, not only as surface-nets, but attached to 

 the dredging-line at various depths, thus giving a 

 tolerably correct idea of the minute inhabitants 

 of the various zones in the water, to what extent 

 they were distinct or intermixed, and whether those 

 found at the surface by night were met with in the 

 under zones by day. 



There are a number of species occasionally met 

 with on the surface, floating on sea-weed carried 

 from the shore far out to sea by the winds and 

 receding tide. Whether in general they take the 

 journey willingly or are carried off by accident 

 may be difficult to determine. The Amphipod most 

 frequently found in this way, during the summer 

 season, is Deocamine spinosa, and the Isopod Idotea 

 tricuspidata. As the latter has been brought up in 

 great abundance by the dredge among wrack (sea- 

 weed) from a depth of twenty fathoms, it is not 

 improbable that their raft of sea-weed from the 

 shore may have got water-logged and taken them 

 safely in concealment to the bottom, which may not 

 be altogether inconsistent with their habits. 



It is a curious fact that the Amphipoda are very 

 seldom taken by the tow-net more than three or 



