184 CRUSTACEA. LOPHVROPODA. 



Gen. 25. ARMADILLO, Lat. Oniscus, Lin. 

 Exterior antennae of seven joints, geniculate, inserted on each 

 side of a notch of the hood ; eyes granular, lateral ; body 

 gibbous and arched ; tail of six segments, the last triangular 

 and short ; appendages of the tail not projecting ; seven pairs 

 of feet. 



A. vulgaris, Lat. Gray cinereous, without spots, and the margin 

 of the segments paler. 6 or 7 lines long. Inhabits Europe, un- 

 der stones. B Shaw, vi. pi. 135. 

 This animal is very common near Edinburgh, under stones, and found at all 



seasons of the year. It rolls itself up into a ball when touched, and will sometimes 



allow itself to be broken rather than unroll its body. 



ORDER VI. LOPHYROPODA. 



Head not distinct from the anterior extremity of the trunk ; eye 

 or eyes sessile and compound ; shell of one or two pieces, and 

 more or less large ; mandibles without palpi ; jaws without 

 branchiae ; feet in variable number, proper for swimming, 

 simple, or branched, or formed of hairy laminae, considered 

 as respiratory organs. 



The Crustaceous animals of this and the following orders were designed collec- 

 tively by Latreille, in the Regne Animal, under the name of Branchiopoda ; by 

 Linnaeus they were chiefly included in his genus Monoculus ; and were named En- 

 tomo&traca by Mutter and others. They are all aquatic, very minute, and microscopic. 

 They have but one sessile and immoveable eye ; the head is not distinct from the body ; 

 and they are covered by a shell or crust. Their feet, or the organs which are called 

 so, are to the number of from six to eight, proper for swimming, and branchiferous. 



FAMILY I. UNIVALVIA. 



Shell of one piece, and leaving the greater part of the body 

 uncovered. 



Gen, 1. CYCLOPS, Muller. Monoculus y Lin. 

 Body oval, conical, elongated ; one eye ; four simple antennas ; 

 two mandibles without palpi, with processes behind represent- 

 ing jaws and pedipalpi ; feet eight, formed of a biarticulate 

 peduncle, and two stalks of three joints ; tail long and fork- 

 ed ; organs of generation at the posterior part of the body. 



The animals of this genus are common in fresh waters, in which they swim by 

 successive leaps. The females are distinguished by their having behind two oval 

 membranous pouches with ova. They are extremely minute, not exceeding n've or 

 six-twelfths of a line long. 



C. vulgaris Leach. (M. quadricornis, Lin.) Body gibbous, formed 

 of four segments ; tail of seven segments ; posterior antennas of 

 four joints, and the anterior ones three times larger, -f^ of a line 

 long. Inhabits Europe. Desm. Crust, pi. 53, fig. 1-4. 



C. staptylinus, Desm. (M. minutus, Fab.) Body elongated, slight- 



