Order =ARTHROSTRACA= (/No carapace, as a rule; six to seven pairs of walking-legs; eyes sessile/) Suborder ~AMPHIPODA~ (/Body usually compressed laterally/) ^Orchestia^ ^O. agilis^ ^Talorchestia^ ^T. longicornis^ ^Gammarus^ ^G. locusta^ ^Chelura^ ^C. terebrans^ ^Caprella^ ^C. geometrica^ Suborder ~ISOPODA~ (/Body depressed or flattened/) ^Cirolana^ ^C. concharum^ ^Limnoria^ ^L. lignorum^ ^Sphæroma^ ^S. quadridentatum^ ^Idotea^ ^I. marina^ ^I. ochotensis^ ^I. metallica^ ^I. wosnesenskii^ ^Chiridotea^ ^C. cæca^ ^C. entomon^ Class =MERISTOMES= Order =XIPHOSURA= ^Limulus^ ^L. polyphemus^ Class =PANTOPODA= (Lang) Order =PYCNOGONIDA= ^Phoxichilidium^ ^P. maxillare^ [pg243] TERMS USED IN DESCRIBING CRUSTACEA ^Abdomen^: The posterior part of the body. ^Antennæ^: Articulated appendages which immediately precede the mouth. ^Anten´nules^: The anterior of the two pairs of feelers of the head. ^Bira´mous^: Having two branches. ^Carapace^: A thin chitinous shell covering the cephalothorax. ^Cephalic^: Pertaining to the head. ^Cephalotho´rax^: The united head and thorax. ^Chela^: The pair of pincers, or claw, which terminates some of the appendages. ^Che´liped^: A leg with chela, or claw, at the end. ^Endop´odite^: The inner one of the two main divisions of the limb. ^Epime´ra^: Divisions on the ends of the segments of amphipods and isopods, and belonging to the legs. ^Epip´odite^: A third branch of a limb. ^Epis´toma^: A triangular area in front of the mouth. ^Exop´odite^: The outer one of the two main branches into which the typical limb of any segment is divided. ^Gastric mill^: The first half of the stomach, where food is ground. ^Mandibles^: The pair of appendages next behind the antennæ. ^Maxil´læ^: The first pair of appendages after the mandibles. ^Maxillipeds^: The three pairs of appendages after the maxillæ. ^Metame´res^: Segments. ^Orbits^: Eye-cavities, peculiar to the higher /Crustacea/. ^Prosto´mium^: The region in front of the mouth; the preoral part of the head. ^Rostrum^: The beak in front of the head. ^Segment^: A part cut off or marked as separate from others. ^Somite^: A segment of the body. ^Squame^: A scale. ^Telson^: The last segment of the abdomen.