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HISTORY OF BRITISH CRUSTACEA. 
Dr. Baird says : “ The mouth-apparatus consists of a large 
well- developed sucking-tube and appendages, adapted for 
puncturing the skin of the animals upon which they live as 
parasites, and for sucking the juices of their bodies; and 
three pairs of foot-jaws, constructed for enabling them to 
fix themselves upon their prey.” When young they undergo 
a series of metamorphoses. 
Bam. ARGtTJLIDJE, Leach. 
Head like a large circular-shaped shield. Antennae short, 
thick, two-jointed ; second pair of foot-jaws replaced by a 
pair of large suckers. (Plate XIX. fig. 1 a , b.) 
Gen. 171. ARGULUS, Mitller. 
Argulus eoliaceus, Linn. sp. Fish Argulus. (Plate XIX. 
fig. 1.) — Rounded-oval; carapace notched on either side 
in front, transparent, slightly greenish, and marked on both 
sides by branched veinings of darker hue. 
Hab. On various kinds of fresh-water fish in the neigh- 
bourhood of London : it is most commonly met with on the 
stickleback. 
Dr. Baird says, it “ is an exceedingly pretty and graceful 
