COMl'FMUf'M OF GENERIC DISTINCTIONS. 



Family. DORIPPIDJE.— Fourth and fifth pairs of legs ele- 

 vated i>n back, not furnished with paddles. Eyes on simple 

 footstalks. 



Verms. Dorifpe. — Claws small, short, and equal; third pair 

 of feet largest, two last pairs having a hooked nail at end. 



Family. CAFHYEIDJE. — Carapace squared, rather convex, 

 slightly wider than long. Eyes retractile. Sternal plate 

 rounded. 



Genus. Caphyra. — Carapace smooth. Pincers with spines 

 on back. Front projecting. Philippines. 



Sub-order. ANOMOURA — Last, or two last, pairs of legs 

 not used for walking, and are set above level of other legs. 



Family. H0M0LID2E. — Carapace beaked i>r spinose. Inner 

 antennae long. Fifth pair of legs not used for walking. 



Genus. Homola. — A series of sharp spines set radiately on 

 the carapace. Eye-footstalks short, eyes very large and 

 rounded. Mediterranean. 



Genus. Lithodes. — Carapace thickly spined. Beak very 

 long;. Fifth joint of outer jaw-feet oblong. Hind-legs re- 

 ceived into branchial cavities. Warm seas. 



Genus. Echidxocerus. — Carapace and limbs thickly noduled. 

 Antennae feathered. Columbia River. 



Family. DEOMJADJS.— Body rather globular; front of cara- 

 pace bent down. Eyes short and looped in their orbits; inner 

 antenna? very short and lodgi d in groove. 



Genus Dromia. — Carapace thickly covered with short hairs. 

 Two hind pairs of legs small, elevated, ending in double claw. 

 Many seas. 



Family. RAJNimujE. — Carapace large and pear-like, the 

 broader end in front. Abdomen small, but partly projecting. 

 All feet except first pair tin-like. Indian seas. 



Genus. Raxixa. — As Family. 



Family. HIPPIDJE.— All upper segments solid. Last pair of 

 legs slender and folded. First segments of abdomen short and 

 broad, last long and triangular. Antennae plumed, ll.it seas. 



Genus. Albuxea. — Claws triangular, compressed. Last 

 joint of next pairs of feet hooked. Carapace flat, squared, btit 

 rounded behind; toothed in front. 



Genus. Remipes.— Claws rather long, conical, and feeble. 

 Antenna? close together. Last joint of second and third pairs 



of feet flat and oar-like. Last segment of abd n long and 



paddle-shaped. 



Genus. Hippa. — Claws egg-shaped and compressed, not fin- 

 gered. Eye-footstalks long and thread-like. Last joint of sec- 

 ond and third pairs of feet triangular, of fourth pair creseentic. 



Family. PAGTJBIDiE.— Abdomen soft, and nearly membra- 

 nous. Two hind pairs of legs very short. 



Genus. Pagurur.— Abdomen turned on itself, a pair of un- 

 symmetrical appendages at tip. Inner antenna' short. Most 

 seas. 



Genus. Cexobita.— Antennae advance, 1; middle pair nearly 

 as Fug as outer. Thorax egg-shaped, conical, long, narrow, 

 and greatly compressed. Indian Ocean. 



'.Vims. BlRUCS.— Abdomen rather solid, having two rows of 

 flattened appendages beneath. Fourth pair of feet about half 

 as large as third pair. Thorax heart-shaped. Indian Ocean. 



Family. PORCELLANIDJE.— Tail ending in swimming-plates. 

 Fifth pair of legs small and folded. Sternal plate wide and 

 circular. 



Genus. PoRfEi.T.AXA. — Carapace wide as long, flattened 

 above, < Inter antenna- very long; outer jaw feet larger. Claw- 

 legs large and flat. Abdomen wide; seven segments; five 

 swimming-plates. 



Sub-order. MACROURA. -Abdomen long, plated, < posed 



of seven segments and with live swimming-plates at tip. First 

 m. segments mostly with a pair of false feet tipped with flat 

 fringed plates. 



Family. GALATHEIDJE — X,, moveable plates to outer an- 



tennae. Body flat; Fifth pair of legs slender, not used fe r 

 walking, and folded. Carapace rather wide and flat, longer 

 than broad, and beaked. Claws rather large. Abdomen larger 

 than carapace. 



Genus. Galathea. — Carapace covered with hairy grooves: 

 beak extended; eyes large; no orbit. Abdomen extended 

 Many seas. 



Family. SCYLLARIDJE. — Carapace wide. Mo moveable 

 plate to outer antenna'. Fifth pair of logs not folded. All legs 

 with one idaw. Outer antenna 1 large and flit; abdomen very 

 wide; swimming-plates partly flexible. In male, first pair of 

 false feet very large, with two wide plates; rest with one plate. 

 Many seas. 



Genus. Sctllarus. — Carapace larger than wide; sides par- 

 allel. Many seas. 



Genus. Ibaccs. — Carapace wider than long, deeply cleft on 

 either side, notched all round. Abdomen with ring-plates, flat, 

 pointed, and wide. Indian seas. 



Family. PALINURID.ffi.— Body cylindrical. Outer antennae 

 thick and long; basal joint very large. Feet with single toe. 

 Sternal plate wide. 



Genus. Palixurus. — Carapace spiny, with three horns in 

 front. Many seas. 



Family. THALASSIN1DJE.— Abdomen long, not very solid; 

 carapace small and compressed. First pair of legs large. Ster- 

 nal plate long and narrow. 



Genus. C.iLLIAXASSA. — Carapace very small, not beaked. 

 Eye-footstalks flat. Third pair of legs wide at end; second pair 

 with two toes. One claw much larger than the other. Many 

 seas. 



Genus. Axics. — Outer antennae long; small moveable spine 

 on footstalk; inner antennae with two long bristles. Claws com- 

 pressed, unequal; last joint of abdomen long and triangular. 

 Many seas. 



Genus. Gebia. — Beak triangular. Outer jaw-feet like walk- 

 ing feet. Abdomen wider in middle than at base; first ring 

 with a pair of little appendages. Many seas. 



'.'cans. CaloCARIS. — Carapace large, beaked. Large trian- 

 gular scale at base of outer antennae. Claws long, flat, and 

 slender. Eyes very small, without .any pigment on cornea. 

 Many seas. 



Finn, hi. ASTACIDiE. - Outer antenna:- with moveable plate 

 at base. Beak moderate, just hiding base of eye-footstalks. 

 Claw feet large; second and third pairs of feet two-clawed; 

 fourth and fifth one-clawed. Side of eai h abdominal ring ex- 

 tended. Cross-joint in each swimming-plate. 



Genus. Homarcs. — Beak narrow, with several teeth. Eyes 

 spherical. Basal [date of outer antenna- tooth-like. Manyseas. 



Genus. Astaits. — Beak wide at base, depressed; one tooth 

 on each side. Fresh running waters. 



Tribe. CARID1TA. — Abdomen very large, horny. Outer 

 antennae with very large plate at base. Base of false feet cov- 

 ered by projections of segments. 



Family. CRANGONIDJE. -Both pairs of antennae on same 

 line. First pair of legs with small pincers. 



Genus. Craxqox.— Carapace flattened; claw also flattened. 

 Second and third pairs of legs \rry slender; fourth and fifth 

 strongest. Many seas. 



Family. ALPHEIDiE. —Antenna- in two rows, nine above, 

 Beak small and flat; three last pairs with one .-law. 



Genus. Alpheus.— Carapace projecting like a hood; beak 

 small or absent. Claw-legs large; unequal. First and second 

 pairs of legs two-toed; third, fourth, and fifth, one-toed. Many 

 seas. 



Genus. Am is vs.— Beak small, not toothed. Three filaments 

 on inner antenna-. First pair of legs large, powerful, and un- 

 equal; pincers thick. Eyes not prominent, but projecting beyond 

 carapace. Many seas. 



Family. PALJEMONID.* Beak long, compressed, and 



