of the Fishery Board for Scotland. 



201 



in various parts of the mainland of Scotland, and Mr. Scourfield (toe. cit.) 

 reports its occurrence as far south as Epping Forest. A. rustica has 

 been obtained in Loch Lomond, Loch Arklct, Loch Achray, and Loch 

 Doon, but was somewhat rare in each of them. 



Alonella exigua, Lilljeborg. — The Alonella which I have here, and in 

 previous papers on the fresh-water Entomostraca of Scotland, recorded 

 under the name of Alonella exigua belongs to the form known as 

 Alonella excisa, G. O. Sars. The shell of this Lynceid has the inter- 

 spaces formed by the reticulations ornamented with numerous very delicate 

 striae. In recording this Lynceid under Lilljeborg's rather than under 

 Sars' name, I follow the authors of the "Monograph of the British 

 Entomostraca belonging to the Bosminidse, Macrothricidse, and Lynceidse," 

 who regarded both as forms of the one species, and accordingly gave the 

 preference to the older name. It may be that both forms are distinct, 

 and if they are so these Scottish Alonellas ought to be called Alonella 

 excisa. This Alonella was moderately frequent in some of the gathetings. 



Harporhynchus falcatus. G. 0. Sars. — This curious Lynceid was 

 observed in five of the lochs examined — Loch Lomond, Loch Arklet, 

 Loch Katrine, Loch Achray, and Loch Doon. It is perhaps a more 

 widely distributed species than it was at first thought to be. 



Chydorus globosus, Baird. — This fine species occurred in only two lochs 

 — Loch Lomond and Loch Achray. Though its distribntion extends to 

 the Shetland Islands, it does not appear to be very common. 



Chydorus coelatus, Schoedler. — This very small form was observed in 

 five of the lochs examined. 



Chydorus (?) latus and Chydorus (?) ovulis are two doubtful forms 

 which may probably be only the young of Chydorus globosus. 



Monospilus tenuirostris, Fischer. — This curious and rare Cladoceran was 

 observed in Loch Lomond, Loch Achray, and Loch Leven. It has been 

 known as a member of the Loch Leven entomostracan fauna for a good 

 many years — at least since 1890. 



PoLYPHEMIDjE. 



Bythotrephes longimaaus, Ley dig. — Bythotrephes has occurred in all but 

 two of the eleven Scottish lochs recently examined. It seems to have a 

 wide distribution among the lochs of the mainland, but it has not been 

 observed in any of the lochs of the Outer Hebrides that I have examined, 

 nor in those of Orkney or Shetland. 



Leptodora hyalina, Lilljeborg. — This entomostracan occurred in each 

 of the lochs in which Bythotrephes was obtained, and it was moderately 

 common in several of them. Leptodora, like that species, has not been 

 observed in the Outer Hebrides or in the Orkney or Shetland Islands ; but 

 its distribution on the mainland extends from the South of Scotland north- 

 ward as far at least as Loch Ness. A careful examination of specimens 

 from various lochs and of various sizes and stages of development has 

 been made in order to ascertain if more than the one species existed in 

 Scotland, but it has failed so far to bring to light any other form than 

 the well-known Leptodora hyalina. 



