DAPHNIA

A genus of the Entomostracous or lower organized Crustaceans, belonging to the order Branchiopod a, and the section Lophyropoda. The most common species and type of this genus, Mon oculus pulex of Linnaeus, is a favourite and interesting microscopic object. Its body is compre ed, oval, and inclosed in a large bilobed carapace; the two lobes being connected together along the back and open below, 'resembling a bivalve shell. The head is prolonged into a snout, and provided with a single central compound eye. The chief organs of swimming are the modified antennae, which have a long basal joint, supporting two jointed branches beset with long bristles. It is bjr the sudden contraction of these organs that the little animalcule propels itself through the water by a series of jerks. The true legs are ten pairs, very small, having a respiratory vesicular organ attached to the second joint; the first eight pairs have the terminal joint dilated and hairy. The eggs are incubated in a kind of marsupial pouch, situated towards the dorsal aspect of the lower end of the body: in five days the young are excluded. The Daphnia pulex is extremely prolific; and as it a umes a rose-red colour in summer time, the swarms which abound in stagnant water often impart to it so deep a colour as to give rise to a suspicion and popular belief that it is occasioned by blood. D A'llIC. A Persian gold coin (so called by the Greeks, from Darius, the name of several Persian sovereigns), having upon the obverse an archer crowned and kneeling upon one knee, and on the reverse a quadrat a incus a, or deep cleft. The weight of the daric is about 130 grains. DAROO' [s. 327]