322 



Part III. — Fifteenth Annual Report 



NOTES ON SOME OF THE SPECIES RECORDED IN THE 

 PRECEDING TABLE. 



Crustacea. 



Gammarus Duebeni, Lilljeborg. 



As has been already stated, this species was obtained in Loch Ruan, 

 near Campbeltown. Loch Ruan is situated several hundred feet above 

 sea-level, and part of the town of Campbeltown obtains its supply of water 

 from this loch ; the occurrence of Gammarus Duebeni in it is therefore of 

 interest, as it tends to show that this amphipod, chough sometimes ob- 

 served in brackish water, is not limited to such conditions. 



Cyclops Leucharti, Claus, PI. IX., figs. 23-25. 



So far as known to me, this species, which is comparatively a small 

 one, has not before been recorded for Scotland. It belongs to the group of 

 Cyclops that are provided with seventeen-jointed antennules, and is readily 

 distinguished from any other British species by the structure and arma- 

 ture of the fifth pair of thoracic feet. This pair of feet, which are of 

 medium size, are each furnished with three moderately long setae, of 

 nearly equal length : one seta is on the basal joint, and two are on the 

 secondary joint ; one of those on the secondary joint springs from a lateral 

 notch, while the other is situated at the apex (fig. 24). This arrange- 

 ment of the setae of the secondary joint is one of the characters that dis- 

 tinguishes Cyclops Leucharti from Cyclops oithonoides, G. 0. Sars. In this 

 species, which, along with the other, has been obtained in England by 

 Mr Scourfield, both setae spring from the truncate end of the secondary 

 joint. In living or in well-preserved adult specimens of Cyclops Leuchartit 

 there is a peculiar hiatus or notch near the end of the hyaline marginal 

 membrane of the last joint of the antennules : this is not shown in our 

 figure, but Dr Schmeil * gives an enlarged drawing of it. It was also dis- 

 tinctly seen in one or two of the specimens from Rescobie Loch. A 

 few of the specimens from Rescobie also carried ovisacs. 



Cyclops varicans, G. 0. Sars (PI. IX., figs. 26-28). 



There are two species of Cyclops that a have somewhat similar appear- 

 ance, and require careful examination to distinguish the one from the 

 other — viz., Cyclops varicans, G. 0. Sars, and Cyclops bicolor, G. O. Sars. 

 Adult female specimens of Cyclops varicans may, however, be distin- 

 guished by the antennules having twelve instead of eleven joints (tig. 

 26) ; and by observing, in the fifth pair of feet, that that part of the 

 basal joint intermediate between the seta on that joint and the secondary 

 branch is not so prominently produced in Cyclops varicans as it i.s in 

 Cyclops bicolor. The secondary joint of the fifth pair in Cyclops vari- 

 cans is small, and bears only one seta; this seta springs from the apex 

 of the joint, which is so small that it looks as if it were merely the basal 

 part of the seta (fig. 27). 



Habitat. — Loch Rescobie and Loch Balgavie ; rare. One or two of 

 the specimens carried ova. I do not know of any previous British 

 record for this species. 



* Deutschlands freileb. Sussw.-Copep. , Part I., PI. III., fig. 3. 



