224 PROCEEDINGS OF THE SOCIETY. 



the most valuable, but he advised the use of nets of at least two different 

 grades of mesh : a coarse net of between thirty and forty threads to the 

 inch for larger forms, whilst one of about 100 threads to the inch was 

 sufficiently fine to secure all but some of the minute larval forms. In 

 addition to the hand-nets, others (preferably of two grades of mesh as 

 before), attached to a line to be used as tow-nets or dredges from a boat, 

 or thrown out some distance from the shore when it was not possible to 

 get a boat, were needed. A small naturalist's dredge might also prove 

 useful when large quantities of bottom material were required. 



A cone-dredge, consisting of a net with a cone of wire gauze over 

 the mouth, which could be thrown out amongst weeds and pulled in 

 quite easily, was used by some workers, who considered it kept out the 

 larger organisms and gave a fairly clean collection of Entomostraca. 

 Apparatus, however, was of less importance than the knowledge of how, 

 when, and where to collect. 



Numerous forms could be secured by carefully working the hand- 

 nets at the margins of ponds and lakes ; but samples from the 

 bottom should also be taken, and in the case of the larger pieces of 

 water the use of the tow-net was essential. On Lake Windermere he 

 had but poor success at the surface during the clay time, rare forms, e.g. 

 Leptodora and Bythotrephes and others, being obtainable only at a con- 

 siderable depth ; but after dark they were abundant on the surface. The 

 most favourable season of the year to collect varied somewhat with the 

 different species; generally speaking, the autumn was the best, not 

 only for the number of species, but also for the probability of obtaining 

 the comparatively rare males and ephippial females of the Gladocera. 

 For the species favouring small shallow ponds and pools liable to be 

 dried up annually, the best time was obviously late spring and early 

 summer. 



Entomostraca were not limited to lakes, ponds, pools, and ditches, but 

 were found often in strange places — in mosses growing just above the 

 water level and in damp hollows, in the roots of aquatic plants, and con- 

 sequently had to be collected by washing the mosses and roots. The water 

 lying in the hollows on the trunks and roots of trees was sometimes the 

 habitation for an apparently new species of Harpacticid, and he had 

 gathered many examples from this source in Epping Forest. Another 

 peculiar Harpacticid, Belisarius, was found in the little cups formed by 

 the leaves of various Bromeliaceous plants kept in hot-houses in this 

 country. 



In the examination of specimens with pocket lens and low powers of 

 the Microscope certain appliances were particularly helpful, such as a 

 black photographic developing-dish for picking out specimens, as the 

 Entomostraca were mostly light in colour, and the contrast aided differ- 

 entiation ; Petri dishes also could be used with either a black or white 

 background or transparently ; small sieves of gauze were most useful 

 for removing the larger organisms, such as snails, insect larvae, etc., and 

 also the fine mud. For isolating specimens little glass evaporating 

 basins (with spout) were very convenient ; and a very small brush was 

 indispensable ; large quantities of material should be spread out on 

 ordinary lantern slide covers which were of thin clear glass of a very 



