INTRODUCTION. 9 



the extreme limit of high water mark, are very 

 frequently tenanted by a single species, Harpacticus 

 f^dvus ) Fischer, which is very rarely to be met with in 

 more purely marine situations. The bed of the sea, 

 down to the extreme depths attainable round the 

 British Islands, is inhabited by numerous Copepoda ; 

 on sandy bottoms the most abundant species are 

 Longipedia coronata, Glaus, and Ectinosoma spinipes, 

 Brady, but Copepoda of some kind are found in greater 

 or less abundance on all sorts of bottoms. One 

 exception must be made to this statement ; in various 

 hauls from a bottom of slimy argillaceous mud, the 

 product of the debris of disintegrating felspar rocks, 

 taken from a depression of the depth of fifteen to 

 twenty-five fathoms at the north end of Mulroy Lough, 

 County Donegal, Mr. Robertson and myself could not 

 detect one trace of life of any kind. The beds of 

 fresh water lakes seem to be very sparsely populated 

 with Copepoda, and as to swimming species it may, as 

 a general rule be said that the weedier the pool and 

 the smaller its extent, the more abundant in all 

 probability, the Entomostraca. 



A few words as to the best modes of collecting 

 Copepoda will not be out of place here. In the case 

 of tidal marine pools and small fresh water ponds, 

 such as may easily be fished from the edge, a common 

 ring net fitted with a muslin bag and attached to the 

 end of a walking stick will answer every purpose. 

 This may be worked to and fro amongst the weeds 



Hylton Dene," by George fe. Brady (' Transactions of the Tyneside 

 Naturalists Field Club,' vol. vi). 



