CRUSTACEA. 
499 
tennae, which are the longest; head nearly as broad as the body, 
almost square; eyes two, round and compound; tail very large, 
with three articulations, and destitute of terminal appendages 
covering the branchiae and their protecting laminae; having four¬ 
teen feet. 
Idotea entomon. — The Entomon Idotea. 
Plate XCV. fig. 1. 
Drab-coloured above, whitish-gray below; antennae nearly of 
equal length. One inch and a half long. Inhabits the Nor¬ 
thern coasts. 
Section II.— Terrestria. 
With two very small, hardly visible* intermediate antennae, 
and having no more than two joints; post-abdomen consisting 
of six segments, the posterior margin of the last one with two 
bifid styles in some, and four in others. 
TRIBE VI.-ONISCIDES. 
This tribe consists of five genera; namely, 21. Ligia; 22. 
Philoscia; 23. Oniscus; 24. Porcellio; and, 25. Armadillo. 
Genus 23. — ONISCUS.— Linnceus. 
Generic Character —With four antennae placed below the 
anterior margin of the head, the two anterior ones setaceous, 
and the only ones which are apparent, the intermediate ones 
being indistinct; eyes sessile ; body oval, and having imbricated 
crustaceous segments; extremity of the tail with two protruding 
appendages. 
Oniscus asellus. — The Ass Oniscus. 
Plate XCV. fig. 4, 
Body somewhat rugose above, most so on the head; dusky- 
gray, paler on the margin ; each side of the body with a longi¬ 
tudinal row of yellow spots. Inhabits the coasts of Europe. 
Genus 25.—ARMADILLO.— Latreille. 
Generic Character. —Anterior antennae seven-jointed, genicu¬ 
late, inserted on each side of a notch on the hood ; eyes lateral. 
