April, 1896.] 89 



NOTES ON COI.LECTING KNTOMOSTRACA, 



WITH A I,IST OF THE IRISH SPKCIKS OF CI,AD0CE:RA KNOWN 



AT PRESENT. 



BY R. H. CREIGHTON, M.B. 



Entomostraca are found everywhere ; they are especially 

 abundant in marshes, the weedy pools on the outskirts of a 

 bog, and in the bed of weeds which exists in most lakes where 

 the deep and shallow waters meet. In the centre of the larger 

 lakes a regular pelagic fauna exists ; it has been little studied 

 in the United Kingdom, as it is impossible to collect it 

 without the aid of a boat. The best time to obtain these 

 pelagic forms is at night, when they crowd to the surface in 

 large numbers, even in the middle of winter. 



For collecting in the smaller pools, the ordinary muslin 

 net and glass bottle at the end of a stick about four feet long 

 answer well. In larger ponds and in lakes of course they are 

 of no use ; here I find Professor Birge's cone dredge (8) a great 

 comfort, as the cone keeps out weeds, insects, larvae, &c. 

 " It consists of four parts, the body, the cone, the net, and 

 the screw-top. The body is a cylinder of stout tin, strength- 

 ened by a wire at each end, four inches long, and four inches 

 in diameter. On top of this is placed a cone of brass netting, 

 five inches high ; this is attached below to a circle of tin so that 

 it fits into the top of the body like the cover of a tin pail. 

 The bail of the body is of stout brass wire, the ends passed 

 through the side of the body and enlarged, and the loop of 

 wire shaped so as to fit within the cone and project through a 

 hole in its top, with an eye into which the dredge-line can 

 be fastened. Two cones are provided, one of one-tenth inch 

 mesh and one of one-twentieth inch. The net is of fine 

 cheese-cloth, eighteen to twenty-two inches long, conical, 

 large enough at the base to slip over the dredge-body to which 

 it is tied. It is faced with stout muslin for a distance of two 

 or three inches at each end. At the smaller end it is small 

 enough to fit the screw-top, a tin cylinder one inch in diameter 

 and one inch and a quarter long, with a wire in one end, and 

 on the other a zinc screw-top such as is used on paraffin 



A 



