CALIGUS. 
269 
Genus 1 — Caligus. 
Caligus, Muller , Entomostraca. 
— Latreille , Cuvier 3 Lamarck, Leach, Desmarest, Nordmann , 
M. Edwards, Pickering and Dana, Kroger, 8fc. 
Monoculus, Linnaeus, Fabricius, Manuel. 
Binoculus, 0. Fabricius, Eaun. Green. 
— Muller, Zool. Dan. Prod. 
Pediculus, Easter, Opusc. Subseciv. 
— Strom , Phys. og Oeconom. Besk. 
Oniscus, Slabber. 
Character. — Fourth pair of feet slender, of only one 
branch, and serving the insect for walking. Thorax ex- 
hibiting only two distinct articulations. Frontal plates 
possessing a small sucking-disc or lunule on the under 
surface of each lateral portion. 
1 . Caligus diaphanus. Tab. XXXII, fig. 1 . 
Caligus diaphanus, Nordmann, Microgr. Beitr., ii, 26. 
— Kroger, Tidsskrift, i, 623, t. 6, f. 5. 
— M. Edwards, Hist. Nat. Crust., iii, 452, No. 5. 
— Thompson, Ann. Nat. Hist., xx, 247. 
— Easter, Op. Subsec., ii, t. 8, f. 9 b (?). 
Description. — Male . Carapace large, and nearly round • 
frontal plate of considerable size ; lunules distinct but 
not large. Antennae of moderate size ; basal joint large, 
and setiferous on external edge. Thorax very much 
smaller than carapace. Penultimate segment very small 
and narrow ; the last somewhat lunulate, the external 
posterior angles terminating in a projecting lobe, which 
is shortly bifurcated, the external fork giving off one, 
and the internal two, short plumose setae. 
Abdomen nearly as long, but narrower than the last 
joint of thorax, and terminating in two pretty large caudal 
