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Part III. — Eleventh Annual Report 



be quite sufficient to account for the difference in depth between the 

 different soundings. The depth of the west portion of the loch was not 

 tested, but the west end is probably comparatively shallow, if one may 

 judge by the numerous islets at that end, and by the contour of the land 

 contiguous to this part of the loch. 



Specific Gravity and Temperature of the Bottom Water. 



The self-locking water-bottle,* which was let down and touched bottom 

 at 145 fathoms, as already stated, was when hauled up found to be per- 

 fectly closed, and filled with water mixed with impalpable mud. This 

 mixture was emptied into a sufficiently large vessel, and when the mud 

 had subsided the supernatant water was run off and tested by one of the 

 set of hydrometers used on board the ' Garland.' The specific gravity 

 registered by this hydrometer was 1007*9; temperature of water at the 

 time the specific gravity was taken, 13-9° C. (57-2° F.) The temperature 

 of the water at the bottom of the loch, taken with a ' Negretti-Zambra ' 

 deep-sea reversing thermometer, was 42° F. ; at 100 fathoms the tem- 

 perature was 49*6° F. j and at the surface, 57*7° F. The water, as in 

 the case of many Highland lochs, was of a brown peaty colour. 



Invertebrate Fauna. 



The bottom mud brought up by the dredge and by the water-bottle at 

 Station IY. was carefully examined, with the result that no living organism 

 could be detected in it ; a considerable portion of it consisted of fragments 

 of Entomostracan tests that. formed a distinct layer on the surface of the 

 mud after it had been allowed to subside ; it thus resembled very closely 

 the mud from the bottom of Loch Ness. The loch was tow-netted in 

 various places from Brinacory eastward to the head of the loch. The 

 tow-net collections were chiefly made at the surface or at a depth of a few 

 fathoms. On one or two occasions, however, the tow-net was attached to 

 the dredge and lowered to a depth of from 50 to 100 fathoms. Ento- 

 mostraca were found to be abundant at and near the surface, but were 

 much fewer at 50 and 100 fathoms : the grouping of the species, 

 however, appeared to vary very little in the surface and deep-water 

 gatherings. A few gatherings were made by dragging the tow-net 

 through the weeds in the shallow water at the head of the locb, and also 

 close inshore at Brinacory — on the north side of the loch, near Brinacory 

 island. Two days were devoted to the examination of Loch Morar, but 

 the weather w r as not very favourable. On the first day there was almost con- 

 tinuous rain ; the first part of the second day was rather better, but a 

 smart westerly breeze sprang up shortly after noon, which caused the 

 water to become choppy, and made rowing more exhaustive and difficult. 

 Mr Anderson Smith accompanied us the second day, and but for his 

 assistance and encouragement our success, small though it may be, would 

 have been less. 



Pelagic Entomostraca, though abundant in Loch Morar at the time of 

 my visit, included comparatively few species, viz., two (or Hhree) species 

 of Copepoda and five of Cladocera; on the other hand, the bottom material, 

 though comparatively poor in number of specimens, was rich in species, 

 especially of CfadOcera, — the number obtained in the bottom gatherings 

 include eight species of Gopejwda, five of Ostracoda, and sixteen of 

 Cladocera. The apparent scarcity of the Ostracod group is noteworthy, 

 and is probably attributable to non-suitability of habitat The physical 



* Vov description of thU ttdtG^bettle, see BMh Amml Report oj? the tfkhnry 

 Swrdfof Scotland, p«r{ lii, kit?, pt x. (1888). 



