A HISTORY OF LANCASHIRE 



these species : in tidal pools near Piel.'^ Discussing Cytheropteron humile 

 (Brady and Norman) Mr. Scott writes : ' Many specimens of this remarkable 

 little ostracod are found by washing water-logged and decayed wood in weak 

 spirit, and examining the sediment. My father, who first found the species in 

 material dredged in the Clyde, tells me that he always finds it when examining 

 the sediment washed from old wood brought up in the trawl net, and remarks 

 that it seems to be partial to that kind of habitat. In water-logged wood 

 burrowed by wood-boring Crustacea, collected between tide marks in Barrow 

 Channel, near Piel, April i8th, 1901.' The wood-boring Crustacea noticed in 

 this passage would no doubt be the isopod Limnoria lignorum (J. Rathke) and 

 the amphipod Chelura terebrans (Philippi). 



From the minute forms of the Ostracoda, self-contained in a kind of 

 natural boxes which they are able to close tightly over all their appendages, 

 we now pass to the much more showy Copepoda. These, however, attain to 

 no majesty of size, and, except in some of the parasitic species, are as a rule 

 diminutive. But there is a vast variety among them, sometimes great beauty 

 of microscopic adornment, and no doubt some of the species attain to con- 

 siderable economic importance by the dense masses of individuals with which 

 they populate some waters. As to the strictly freshwater denizens of this 

 county, it happens that the records are rather scanty, the attention of local 

 investigators having been for the time principally fixed upon the marine 

 fauna. The chief specialists on this group are not entirely unanimous as 

 to the principles on which its internal classification should be based, and 

 for the moment the lines which the leading authorities propose to follow are 

 not completely mapped out. In arranging the order of our local species we 

 are therefore unable to follow any single guide, but must be content with a 

 systematic framework as harmonious as the indications already divulged allow 

 us to make it. The family Calanidas has recently been much subdivided by 

 Professor Sars. Accepted in the wider extension allowed it by Giesbrecht 

 and Schmeil,* it supplies Lancashire with one of the smallest known Calanids, 

 Paracalanus parvus (Claus), from the mussel beds at Piel,' and with Stephos 

 gyrans (Giesbrecht), obtained by Mr. A. Scott 'amongst material collected in 

 Laminaria bed, near Piel, at a very low ebb.'* Mr. I. C. Thompson speaks 

 of '■ Pseudocalanus elongatus (Baird) ' as 'very common throughout the district, 

 and seldom absent in any tow-net gathering.' ° The name should properly 

 read Pseudocalanus elongatus (Boeck). It is right to mention that the late 

 Mr. I. C. Thompson, F.L.S., applied himself with enthusiastic industry to 

 investigating the marine Copepoda not only of this county but of all the neigh- 

 bouring waters, and that his labours have been supplemented in the same 

 productive field by a worthy coadjutor and successor, Mr. Andrew Scott, A.L.S. 

 Among the numerous species brought to light by their researches I propose 

 as a rule to introduce to the readers of this chapter only those which have 

 been definitely assigned to Lancashire localities, with merely an occasional 

 reference to those spoken of in general terms as belonging to the district. 



The family Diaptomidas, corresponding with the Centropagidae of Gies- 

 brecht and Schmeil, may be credited here with at least four species, namely, 

 Diaptomus castor (Jurine), of which ' Mr. Weightman met with specimens of 



1 Op. cit. XV. 347 (1901). 2 Das Tterrelch, 'Copepoda Gymnoplea ' (1898). 



* Trans. Liverp. Biol. Soc. x. 127. * Op. cit. xv. 348 (1901). ^ Op. cit. vii. 181 (1893). 



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