90 The Irish Naturalist. [April, 



cans." This dredge can be thrown easily twenty yards from 

 the shore and hauled in by the line, thus collecting much more 

 extensively than it is possible to do with the ordinary hand- 

 net. It can be pulled through weeds, and can strain a large 

 quantity of water without getting filled with vegetable debris. 

 When used as a surface net the cone is removed. 



Bntomostraca are best examined alive in a drop of water, 

 either in a hollow-ground slide or on an ordinary slide, the 

 pressure of the coverglass being taken off by a pellet of wax, 

 or as Professor Hartog suggests, a frond of Duckweed. If 

 unable to examine them at once, remember that they live 

 much longer if kept in the dark. 



Mounting permanent specimens is very troublesome. I get 

 the best results by killing with osmic acid, bleaching carefully 

 with chlorate of potash and hydrochloric acid, grading 

 through alcohol, staining with tincture of cochineal or with 

 hsematoxylin (the latter is very liable to overstain), and 

 mounting in Canada balsam. Prof. Herman Fol advises 

 killing with tincture of iron (steel drops) added to a small 

 quantity of water in which the animal is swimming, and sub- 

 sequent staining with gallic acid. I have not had much 

 success with this method. Sometimes, more especially with 

 the smaller Cladocera, the osmic acid alone gives sufficient 

 differentiation. Kleinenberg's picro-sulphuric acid is useful 

 for killing, and has the great advantage of being cheap. If 

 you use it, remember to wash out with dilute alcohol, not 

 water. 



For preserving specimens for future study glycerine does 

 well for Copepods ; the following is a good formula : — gl}^- 

 cerine one ounce, proof spirit two ounces, w^ater one ounce, 

 liquefied carbolic acid one dram, mix. They can be examin- 

 ed in this solution without staining, and can be mounted out 

 of it in glycerine jelly. Cladocera are much harder to deal 

 with ; I get the best results by killing with osmic acid and 

 gradi-ng carefully through 30, 50, 70 and 90 per cent, alcohol ; 

 but it is much better, in fact almost essential, to examine 

 specimens of this group alive. 



In the following list I have endeavoured to collect all the 

 species recorded from Ireland ; they number only 23 ! In a 

 S3aiop,sis of the British Cladocera published in \\i^ Jommal oi 



