OBSERVED DEPTHS IN LOCH LOMOND. 141 



been known to spread beyond its limited area. 

 Many other similar instances might be adduced of 

 plants and animals persistently clinging to a par- 

 ticular spot, without any very obvious reason for 

 their so doing. 



Observed Depths in Loch Lomond. 



[Read 3rd August, 1886.] 



Some years ago I was desirous to ascertain at what 

 depth of fresh water Ostracoda were to be found ; 

 and the great depth of Loch Lomond offering a good 

 opportunity for observation, my son and I proceeded 

 to Tarbert, which is near that portion of the loch 

 marked on the chart as having a depth of 105 fathoms. 

 We were fortunate to find at the hotel a boatman 

 who had assisted in taking the soundings of the 

 loch many years previously. Under his guidance, 

 and without much trouble, we reached the 105 

 fathoms, the area of which depth we found not to 

 extend to any great distance. 



No Ostracoda were met with, nothing being found 

 but a few Foraininifera of the genus Defflugia ; but 

 Ostracoda were moderately common further down 

 the loch, the species being chiefly Candonaz. Whether 

 their range was determined by the depth of water, 

 or the want of circulation in that deep part, it may 

 be difficult to decide. 



In connection with this point, a somewhat similar 

 result was experienced when dredging in Millroy 

 Lough, County Donegal, Ireland, in company with 

 Dr. G. S. Brady of Sunderland. The lough, accord- 

 ing to my recollection, is about 7 or 8 miles long, 

 by 3 or 4 broad ; the sea enters by a narrow channel, 

 and the general depth is about 6 or 7 fathoms. It 

 is rich both in animal and vegetable life ; but at one 

 end there is a deep portion of 25 fathoms, where 

 life appears to be almost absent. This we attributed 

 to the want of circulation, in consequence of a 

 barrier of shallow water between the deep trough 

 and the inlet and outlet channel. 



