60 Oji Australian Entomostracafis, 



many months, under almost daily observation, I have fre- 

 quently seen them attack other Entomostraca, such as 

 Limnadia and Daphnia, almost before death ; and soon 

 after death the shell has been found emptied of all its con- 

 tents by these minute gourmands. A dead Limnea or 

 Planorbis, or other small mollusk, is quite a dainty ; and 

 hundreds may be seen heaped one upon another in a perfect 

 turmoil of delight, each striving to get at the savoury 

 morsel. '' Nee mora nee requies." And no alderman quits 

 a civic feast with greater reluctance than these Cypridoe 

 manifest when driven away from the sumptuous repast. 

 This habit makes them of essential service in preventing 

 the water from being corrupted by decaying animal matter ; 

 as soon as a leaf or stalk begins to decay, it is covered with 

 these little Crustacea. Yet I have doubted whether they 

 attack it for its own sake, or for the sake of the animalculse 

 which may be feeding on it, for they generally desert it 

 before it has quite disappeared. This is not the case when 

 they are feeding on dead animal matter. 



If we may judge from the shell of the genus Cythereis, 

 (Jones), the genus Newnhamia supplies another link be- 

 tween the marine and fresh water Entomostraca. Mr, 

 Baird has discovered a fresh water Cythere in England ; 

 and here in Australia we have an animal closely connected 

 with the marine genus Cythereis. Both Newnhamia and 

 Cythereis have two eyes, and a very tuberculose shell, and, 

 indeed, the shell of the former is only separated from that 

 of the latter by the flat plate at the ventral margin, by which 

 it is enabled to cling to the surface of the water. I would 

 therefore suggest the following as, in my opinion, a natural 

 arrangement of the genera of the Ostracoda : — 



