CRUSTACEA. . 631 
genus Chalimus BurM. containing young Caligi. His conjecture has been 
confirmed by the observations of Fr. MUELLER, vid. Archiv f. Naturgesch. 
1852, s. gt, Tab. IV. figs. 5, 6. 
Family VI. Argulina. Shell membranous, seutiform, placed 
upon cephalothorax, extending posteriorly into two wings that 
receive the body between them. Compound eyes, two. Antenne 
four, concealed under cephalothorax, short; the anterior biarticu- 
late, recurved, the posterior quadriarticulate. Rostrum acuminate, 
situated in front of aperture of mouth. Six pairs of feet, the feet of 
the first pair being changed in adults into two suctorial acetabula ; 
the feet of the second pair short, with basal joint aculeate, the last 
eight feet cloven into two oars or pilose cirri. Tail short, bilobed, 
behind the sixth pair of feet. 
Argulus Murtu. (Characters of the family). 
Sp. Argulus foliaceus JURINE, Monoculus foliaceus L. Fauna Suec. 2044, 
Herm. Mém. aptérol. Tab. vi. fig. 11, Kocu in PANZER u. HERRICH- 
Scumrrer Ins. Deutschl. Heft 186, Tab. 20. This little parasitic crusta- 
cean lives in fresh water, and attaches itself to fishes (especially Gasterosteus 
pungitius) and to tadpoles. The suckers which had originally the form of 
fore-feet, are only developed after the fourth moult. Compare on this 
species the beautiful memoir of JURINE, the son, in the Ann. du Muséum 
d’Hist. nat. vu. 1806, pp. 431—459, Pl. 26, from which the figures of 
Desmarest (Crust. Pl. 50) are borrowed, and C. Voer Beitrége zur Natur- 
gesch. der Schweizer-Crustac. Neue Denkschr. der allg. Schweizerischen 
Gesellsch. f. d. gesammt. Naturwissensch. Bd. vit. 1845, Pp: 3—16, Tab. I. 
figs. I—12. 
Orper III. Lophyropoda Larr. (Entomostraca EpWARrDs). 
Mouth not produced into a rostrum, not suctorial; mandibles 
suitable for manducation, maxillz lamellose. Feet never more 
than ten, natatory, not foliaceous, often cloven into two oars, 
furnished with setz or cilia. A single eye or two eyes, sessile. 
Tuft-footed, or Oar-footed Crustaceans. Most of the known 
species are from fresh-water, and all are of small size ; their motions 
are rapid and frequently interrupted. 
Comp. on this order: 
Muetu. Entom. (Entomostraca seu Insecta testacea, que in Aquis Danie 
et Norvegie reperit, descripsit et iconibus illustravit O. F., MUELLER, Lipsiz 
et Haunie, 1785, 4to.);—JurinE, Hist. des Monocles qui se trouvent aux 
environs de Geneve, 1820, 4to. av. fig. 
