254 
December 10, 1850. 
Prof. Owen, Y.P., F.R.S., in the Chair. 
The following papers were read :— 
1. Description of several new species of Entomostraca. 
By W. Baird, M.D., F.L.S. etc. 
(Annulosa, PI. XVII. XVIII.) 
Legion Branchiopoda. 
Order Phyllopoda. 
Family Apodid^e. 
Genus Lepidurus, Leach. 
1. Lepidurus viridis, Baird. (PI. XVII. f. 1.) 
Body of animal, including the flap of tail segment, about two inches 
long and one broad. The carapace and whole body are of a fine green 
colour, the carapace covering about two-thirds of the abdomen; the 
edges of the notch in the posterior part of carapace are strongly 
toothed, and those of the inferior half of the carapace are very finely 
serrated; these teeth are of two sets, the one much larger than the 
others; the larger teeth are of a green colour, tipped at the point 
with dark brown ; they are about eleven in number, and between each 
there are two or three much smaller ones interspersed. The appen¬ 
dages of the first pair of feet are very short and small, scarcely ex¬ 
tending beyond the edge of the carapace. The segments of the abdo¬ 
men are each studded with a row of stout, slightly curved spines of a 
green colour tipped at their edges "with dark brown. The tail flap is 
oval, keeled down the centre, the keel being beset with short sharp 
spines, and the edges of the flap are finely serrated. The long setae 
of the tail are nearly the length of the whole animal, and are covered 
with short hairs. 
Hah. Van Diemen’s Land. British Museum. 
Legion Lophyropoda. 
Order Ostracoda. 
Family Cypridid.e. 
Genus Cypris, Muller. 
1. Cypris Donnetii, Baird. (PI. XVIII. f. 19-21.) 
Carapace valves elongate oval. Anterior extremity narrower than 
posterior, and considerably flatter; posterior extremity rounded and 
very convex; dorsal edge arched; ventral slightly reniform. The 
surface of the valves is smooth and shining, of a brown colour, varie- 
