AMPHIPODA AND ISOPODA OF THE FIRTH OF CLYDE. 47 



In Karnes Bay, Millport, they are very abundant 

 from low-water up to about three-quarters tide-mark. 

 From thence down to about half-tide their tracks 

 are very numerous, and pass in all directions and 

 at all angles and curves, a little under the sand, 

 raising it up into tiny rough ridges. When the 

 animal works a little deeper, the ridges are rounder 

 and smoother. When above ground they make little 

 furrows in the sand. That the ridges are more 

 numerous a little above half-tide appears to be 

 accounted for by the fact that the animals have 

 more time between tides to extend their burrows 

 than nearer low -water. In a small fresh -water 

 stream that runs down over the sandy bay, they 

 are found in the sand near high-water. 



To test how long they could live in purely fresh- 

 water, ten of this species were put into rain-water. 

 In a few minutes they seemed to suffer from the 

 change, and now and again darted to the surface, 

 then allowed themselves to drop down to the 

 bottom, back downwards, rising again to the surface 

 and repeating over and over the same movements. 

 Occasionally, when half down, they would re-ascend 

 to the surface, making a few dashes hither and 

 thither, and then dropping again to the bottom. 

 By two-and-a-half hours eight of them were dead, 

 and the other two nearly so. Suspecting that some- 

 thing might be hurtful to them in the water from 

 the rain-barrel, I took more of the species from the 

 sand in the middle of the stream at about half-tide, 

 and put them in a vessel containing water taken 

 from the same part of the stream. In two hours a 

 few of them were dead, but the others were living 

 next morning, and most of them on the surface. 

 A number of the same species, taken from the same 

 place, were put into pure sea-water in the afternoon. 

 Next morning they were all right, sporting through 

 the water, but none on the surface. Again, another 

 batch was taken from very low water, away from 

 any fresh-water, and put into water from the stream 



