of the Fishery Board for Scotland. 



197 



seuted ; these figures were prepared from Loch Ness and Loch Lochy 

 specimens. In the Loch Oich Daphniai the predominant type of head, 

 whether it be acutely or bluntly crested, and whether the crest be upright 

 or inclined, is in its general outline more or less triangular ; whereas the 

 usual form of head met with among the Loch Ness and Loch Lochy 

 Daphnice is more or less flat and rounded, and where a crest is developed 

 it usually starts more or less abruptly from the broadly rounded head ; 

 figures 11 and 12 may be cited as examples. There is, of course, some 

 overlapping of the variations in the several lochs ; still it seems to be the 

 case that while in Loch Oich the triangular and gradually tapering form 

 of head is the more general form, the broadly rounded and abruptly 

 apiculate head is more typical of the Daphniw of Loch Ness and Loch 

 Lochy. These differences, however, have only been observed amongst 

 the females. The males that have been observed in Loch Ness and Loch 

 Lochy are identical in form with those observed in Lech Oich ; and the 

 remarks on the variations noticed in the males of that loch are equally 

 applicable to those of the other two. It may be added that figures 15 and 16 

 represent forms closely resembling that on Plate IX. of Dr. Brady's 

 " Eevision" already referred to, and described by him as D. galeata var. 

 obtusifrons, G. O. Sars ; but Dr. Brady, referring to this variety, says : 

 " I can scarcely think that this form is a permanent one, or that it repre- 

 sents more than a transitory condition." Still the distinguishing by name 

 of the different gradations observed should be useful for reference. It is 

 by no means singular that there should be some difference between the 

 forms of individuals from Loch Ness and Loch Lochy and those from 

 Loch Oich, when the physical conditions of Loch Oich are taken into 

 account, and when they are compared with those of the other two lochs. 

 Loch Oich is comparatively a small loch ; its average depth is considerably 

 less than that of the other two ; and it is also more sheltered. Moreover, 

 its surface is broken up by several small islands and headlands, and its 

 range of temperature is greater. All these differences will doubtless 

 react to some extent on the fauna — at least, on the pelagic fauna — of the 

 loch ; and those organisms that are more readily affected by such differences 

 will exhibit variations more or less obvious. And if, taking into account 

 the physical contrasts referred to, the occurrence of certain modifications 

 in the form of those organisms more readily affected by such differences 

 should not be considered remarkable, neither need it be considered strange 

 that the Daphnice of these lochs, and especially of Loch Oich and Loch 

 Ness, should belong to the same species ; for the direct overflow of Loch 

 Oich by the River Oich is into Loch Ness, and therefore a more or less 

 close identity of species may reasonably be expected to exist between them. 

 Another point that should be remembered is that a considerable amount 

 of Loch Oich water finds its way into Loch Lochy by means of the 

 canal ; but how far this may have an influence in equalising the fauna of 

 these two lochs may be a somewhat more difficult question to solve. It 

 is very probable, however, that the continual daily movement of Loch 

 Oich water south-westward into Loch Lochy via the canal will have a 

 tendency to transport some, at least, of the free-swimming forms from the 

 one loch to the other, and thus extend the distribution of such species. 



There is still another point that may be noticed before passing on from 

 the consideration of the Daphnice of these lochs. Glen Garry, which 

 extends in a nearly east and west direction, terminates at Loch Oich, and 

 the River Garry, which flows through the glen, empties itself into that 

 loch. This river passes in its course through two small lochs — Loch 

 Quoich, near the west end of the glen, and Loch Garry, near the east end. 

 Indeed, one would not be far wrong in considering these lochs as being 



