Daphnia

Fresh-water flea, apparently similar to Cy clops and Cypris, but different in structure. The protruding head bears a pair of bold, biramous antennæ and a dancing, prominent eye, apparently situated ventral of the antennæ. There are five pairs of short feet, and the brood-pouch is formed between the back and the carapace, and bounded posteriorly by a backward proce from the upturned end of the abdomen. The shell ends in a tail-like spine. See CLADOCERA.