174 CRUSTACEA. AMPHIPODA. 



A. rubricate*, Leach. Colour red. Inhabits coasts of Devonshire. 

 Desm. Crust. 268. 



Gen. 5. DEXAMINE, Leach. Cancer, Mont. 

 Four anterior legs subequal, monodactyle, with a filiform sub- 

 ovate hand ; second joint of the four antennae long and slen- 

 der ; eyes oblong, not prominent, inserted behind the supe- 

 rior antennas ; tail on each side with three bifid styles, and 

 above with one moveable style. 



D. spinosa, Leach. Segments of the abdomen behind produced into 

 spines. Inhabits coasts of Britain Desm. Crust. 263. 



Gen. 6. GAMMARUS, Fab. Lat. Cancer, Lin. 

 Superior antennae with a small jointed setae at the base of the 

 fourth joint; four anterior feet with a broad compressed 

 hand, and a strong moveable hook or finger ; the following 

 four simple ; the last six long, raised on the sides of the 

 body, with the terminal joint thin and straight ; long bifid 

 setae on each side of the tail, which is terminated by three 

 pairs of elongated bifurcated appendages ; body oblong, com- 

 pressed. 



The type of this genus is the small crustaceous animal found in clear fresh waters. 

 It swims always at the bottom lying on its side, and its principal means of progres- 

 sion consist in rapid strokes with the appendages of the tail* 



G. pulex, Lat. Body yellowish ; eyes black ; process between the 

 antennae rounded and obtuse. 7 lines long and two lines broad. 

 Inhabits Europe Pen. Brit. Zool. iv. 28. 



G. marinus, Leach. Process between the antennae subacuminate. 

 Inhabits coasts of Devonshire. Lin. Trans, xi. 359. 



G. locusta, Leach. Eyes linear, almost lunate ; antennae with scat- 

 tered hairs j last segment of the tail spinous above. Inhabits 

 shores of France and England. Lin. Trans, ix. 92. 



Gen. 7. PHEEUSA, Leach. 



Superior antennae with no setae at the base of the fourth joint ; 

 tail simple above ; hands filiform. 



f.fucicola 3 Leach. Grayish cinereous, mottled with reddish. Inha- 

 bits fuci on the coasts of Devonshire. Sup. Encyc. Brit. i. pi. 21. 



Gen. 8. ORCHESTIA, Leach. Oniscus, Pallas. 

 Four anterior legs of the male monodactyle ; second pair with 

 a compressed hand; of the female with the anterior pair 

 monodactyle, the second didactyle ; superior antennae not 

 longer than the first two joints of the under ones. 



O. littorea, Leach. Head small ; forceps of the second pair of legs 

 very large ; tail composed of three bifid appendages, the middle 

 one shortest; colour pale green, shading to reddish. Inhabits 

 British coasts, under stones not in the water. Desm. Crust. 261. 



