of the Fishery Board for Scotland, 223 



conditions of fresh-water lochs — as Loch Ness and Loch Morar, where the 

 water is of great depth, and where the shores dip rapidly, leaving very 

 little or no shallow margin — do not seem to favour the development of 

 the Oslracoda ; and it is interesting to compare in this respect the distri- 

 bution of the marine species of the same group, which extends from the 

 shore down to many hundreds of fathoms. Another point of interest 

 maybe noted here, viz., though several species of Copepoda were obtained, 

 including one or two rare ' Harpactids, not a single Canthocamptus was 

 observed, — not even Canthocamptus minutus. Gammarus pulex — the 

 common fresh-water amphipod — was also conspicuous by its absence. 



Mollusca appeared to be very scarce : the only species observed were 

 Limnwa peregra and Pisidium pusillum. 



LIST AND DESCRIPTION OF SPECIES. 



CRUSTACEA. 



COPEPODA. 



Family Calanid/E. 



Genus Diaptomus, West wood. 



Diaptomus gracilis (G. O. Sars). 



1863. Diaptomus gracilus, G. O. Sars, Oversigt af de indenlandske 



Ferskvands copepoder, p. 9. 

 1891. Diaptomus gracilis, Brady, Revis. Brit. Cyclop, and Calan., 



p. 29, PI. XII. figs. 7-9 ; Pi. XII. figs. 1-8. 



Of common occurrence all over the loch, but comparatively few of the 

 specimens mature. 



Family Cyclopid7E. 

 Genus Cyclops, Muller. 



Cyclops viridis (Jurine). 



1820. Monocidus quadricornis viridis, Jurine, Hist, de Monocles, 



p. 46, PI. III. fig. 1. 

 1891. Cyclops viridis, Brady, op. cit., p. 17, PI. V. figs. 6-10. 



Common all over the loch. 



Cyclops scrrulatus, Fischer. 



1851. Cyclops scrrulatus, Fischer, Bull. Soc. Imp. Moscow, vol, 



xxiv. p. 423, t. x. figs. 22, 23, 26-31. 

 1891. Cyclops serrtdatus, Brady, op. cit., p. 18, PI. VII. fig. 1. 



Frequent in bottom material collected at the head of the loch and at 

 Brinacory. 



Cyclops eivarti, Brady. (PI. VI. figs. 1-10). 



1888. Cyclops eivarti, Brady, Sixth Annual Report of the Fishery 



Board for Scotland, Part III. p. 232, PI. VIII. figs. 1-10. 

 1891. Cifclops e/carti, Brady, Revis. Brit. Cyclop, and Calan., 



p. 22, PI. VII. figs. 4-7. 



Length 1*5 mm. (^f-fch of an inch). Seen from thg dorsal view, body 

 elongate, pyriform, tapering gradually to the abdomen ; first pephalo* 



