of the Fishery Board for Scotland. 258 



(Isopoda) described as distinct species one or two forms which previously 

 have apparently been included with the Isopod known as Idotea tricuspi- 

 data, which was in consequence considered to be a variable species. One of 

 the forms referred to, which Professor Sars has raised to specific rank is 

 named by him Idothea neglecta* and he states concerning it that it 

 11 occurs along the whole Norwegian coast from Christiania Fjord to Vadso, 

 and is often found in great abundance among decaying algae in depths 

 ranging from six to twenty fathoms." This form is probably not un- 

 common round the coasts of Scotland, and is, I think, included among 

 the varieties of ' Idotea tricuspidata ' described in Bate and "Westwood's 

 Sessile-eyed Crustacea.f Idothea neglecta appears to be moderately 

 frequent in some parts of the Clyde estuary • my friend Mr. Alexander 

 Patience of Glasgow, who first directed my attention to its occurrence in 

 the Clyde, has obtained a considerable number of specimens, which he has 

 been kind enough to let me examine, and there are several specimens in 

 the collection in the Fishery Board's Laboratory, Bay of Nigg, which are 

 also from the Clyde district. The average size of the male of this Idothea 

 is stated by Sars to be 25 millimetres in length ( = 1 inch). One of the 

 specimens in the Laboratory is, however, much larger than that, being 33 

 millimetres, while others in the same collection measure 28, 27, 25, and 

 20 millimetres. The female is much smaller than the male, its average 

 size being, according to Sars, only 16 millimetres. All the specimens in 

 the Laboratory have been collected in different parts of upper Loch Fyne 

 during 1897 and 1899. 



Idothea neglecta has not yet been recorded from the east coast of 

 Scotland. 



SYMPODA. 



Eudorellopsis deformis (Kroyer). This curious little species was 

 obtained in a plankton-sample collected by the s.s. " Glenogle " about 

 fifty miles to the eastward of the May Island, Firth of Forth, on August 

 20th, 1903 ; the species has been observed in various other localities, but 

 very sparingly and usually in moderately deep water. 



Pseudocuma similis, G. O. Sars. This species has already been referred 

 to as the host of Sphceronella pygmwa under the Cboniostomatidse ; a 

 few specimens occurred in a plankton-sample collected in moderately deep 

 water about three miles off Lossiemouth, in the Moray Firth, on December 

 29th, 1903. Pseudocuma similis resembles the more common P. cercaria 

 very closely, and this may be the reason it has only recently been 

 recognised as a British species. 



A considerable number of other microcrustaceans, more or less interest- 

 ing, have been noticed in various plankton-samples collected during the 

 recent fishery investigations carried out under the direction of Dr. Fulton 

 in the North Sea and Moray Firth. These may be described in a sub- 

 sequent paper dealing more generally with that group of marine organisms. 



I take this opportunity to substitute other generic names in room 

 of two that have recently been adopted for certain forms of Copepoda, 

 but which I now find to be pre-occupiecl. 



(a). Genus Platypsyllus, T. Scott, Twentieth Report of the Fishery 

 Board for Scotland (1902), Pt. III., p. 455. I find that Platypsyllus 

 was used in 1869 both by Dr. Ritsema and Professor Westwood for a 



* Crustacea of Norway, vol. ii., p. 84., pi. xxxv. fig. 1. 

 f British Sessile-eyed Crustacea, vol. ii., p. 381, text figs. 



