642 ARTICULAIA. 



ORDER IV. AMPHIPODA. 



Head separated from the segment which supports the second feet jaws ; 

 the post-abdomeu provided with branchial and narrow elongated swimming 

 appendages below, which are striated transversely, and with maoy articu- 

 lations, or branchiae ; mandibles having palpi. 



This order contains twenty-one genera. 



ORDER V. — ISOPODA. 



Head distinct ; mandibles without palpi ; three psurs of jaws, the lower 

 one like two small feet, united at their base ; or having a lip with palpi ; 

 body depressed, and divided into from three to seven segments ; from ten to 

 fourteen feet; tail with seven segments, or upwards; having branchiae; 

 frequently covered with laminae; destitute of shell ; with four antennae and 

 granulated eyes. 



This order contains twenty-five genera; of which we have figured the 

 following examples : — 



Anthura gracilis.— The Slender Anthura. Plate Ixxxiii. fig. 9. AntenniB 

 short, somewhat equal, the intermediate a little longer than the lateral ones ; 

 body linear ; anterior feet with moveable claws ; tail foliaceous and oblique- 

 )y truncated. 



Idotea entomon. — The Eiitomon Idotea. Plate Ixxxiv. fig. 1. Drab-co- 

 loured above, whitish-gray below ; antennae nearly of equal length. One 

 inch and a half long. Inhabits the Northern coasts. 



Armadillo vulgaris. — The Common Armadillo. Plate Ixxxiii. fig. 6. 

 Ash-coloured, with the margin of the segments paler. Inhabits Europe, 

 under stones. 



ORDER VI. LAPHTROPODA. 



Head not distinct from the trunk; eyes compound and sessile; shell of 

 one or two pieces, and varying in size ; jaws unprovided -with branchiae, and 

 tlie mandibles without palpi ; feet variable in number, simple, branched, or 

 formed of hairy laminae, fitted for swimming; these are considered the or. 

 gans of respiration. 



ORDER VII. — PHYLLOPODA 



Head not distinct from the trunk ; eyes approximate, smooth, and sessile ; 

 antennae very short ; a crustaceous shield, free posteriorly ; having two cor. 

 neous mandibles without palpi ; feet of the first pair oar-shaped, the other.^ 

 fitted for swimming, and consisting of sixty pairs. 



ORDER VIII. — XyPHOSURA. 



Body subdivided, without a syphon ; base of the feet, except the last two, 

 gpiny, and acting as jaws ; shell covering the whole body, hard, in two com- 

 partments, longitudinally furrowed above ; body terminated by a hard sabre- 

 shaped process. 



ORDER IX SIPHONOSTOMA. 



With a syphon or proboscis, but is sometimes invisible, and provided with 

 palpi for suction; with more than six or seven pairs of feet; shell of on« 

 piece, soft, membranous, and not entirely covering the body. 



