344 THE CANADIAN NATURALIST. [Sept. 



swarming of the pink Daphnia or Water-flea has occasionally 

 reddened pond-water so strongly as to have seemed supernatural 

 to our ancestors, and to have produced terror, as an evil omen, 

 among the ignorant. Amongst the British Ostracoda, Ci/pris, 

 Cypridopsis, Notodromas, Gan&ma, are inhabitants of lakes, 

 ponds, ditches, streams, and rivers; and they can be readily 

 obtained and conveniently kept and studied in the aquarium. 

 Paraci/pris, Pontocypris, Bairdia, and Macrocypris, are marine 

 members of Mr. Brady's group " Cypridae." Excepting the 

 fresh-water Limnocy there, all the Cytheridce are marine, Cijthe- 

 ridea and Loxoconcha having also a taste for brackish water. 

 These salt-water species of the Bivalved Entomostraca are 

 distributed in deep and shallow seas, in pools on the beach 

 between tides, in lagoons and back-waters, and in the brackish 

 water of estuaries and salt-marshes. The ' Trans. Zoolog. 

 Soc, 1867, contains a memoir, by Mr. Gr. S. Brady, descrip- 

 tive of some new forms of Ostracoda, in which we find some 

 "habitats " referred to as being in "shallow water,'" and others 

 at 14, 17, 30, 43, 60-70, 223, 360, 470, and even 2050 fathoms. 



The Cyprida, having plumose " antennae," or natatory limbs, 

 possess a greater or less power of swimming, Gandona being a 

 marked exception. On the other hand, the anterior locomotive 

 limbs of the Cytlieridce have usually short setae and hook-like 

 spines, instead of bunches of long, delicate filaments ; and conse- 

 quently these animals crawl about on the weeds, shells, and mud, 

 and few among them can swim at all. 



The ( h/pridinidcB are mostly free-swimming, oceanic forms. 

 Mr. Brady observes that "some of the members of this family 

 have very slight swimming powers, and live chiefly amongst 

 mud ; others are very agile swimmers, and are often taken in the 

 towing-net — more especially at night — near the surface of the 

 sea. They seem, indeed, to contribute very materially to the 

 production of the wonderful phosphorescence of the tropical seas" 

 (' Intellectual Observer,' 1867, p. 115.) 



The removal of dead animal matter is easily accomplished by 

 Entomostraca and other small Crustacea; and, as the Emmets 

 and their little fellow-labourers pick bare the bones of large land 

 animals, so these minute creatures of the water use up the dead 

 bodies of the animals in the ocean, the lakes, and rivers, foraging 

 for the dead zoophyte, and swarming over the lifeless mass of 

 mollusc, annelid, and star-fish, and taking their share of the dead 



