AMPHIPODS 289 
are distinctly marked, and it terminates in long, forked spines, which 
are longer than the telson. It is found from New Jersey northward. 
ORDER ARTHROSTRACA 
SUBORDER AMPHIPODA 
The Amphipoda have a laterally compressed body, with gills onthe 
thoracic feet and an elongated abdomen. The segments of the 
thorax are not united, nor covered by a carapace, but the whole 
body is covered with a segmented, polished, flexible cuticle. The 
three anterior legs of the abdomen are for swimming-feet, and 
the posterior ones are adapted for springing. The antenne are 
long and hairy. The amphipods comprise the beach-fleas and 
many other small crustaceans which abound between tide-marks 
on all beaches. Besides serving in no small measure as food for 
fishes, they are scavengers of the beach, and consume large quan- 
tities of waste matter. They are sometimes used in preparing 
skeletons for anatomical specimens. Animals to be skeletonized, 
being fastened to boards and anchored just below the surface of 
the water in sheltered places, are divested of all flesh in a few 
hours, and the bones are more completely cleaned than if pre- 
pared by a naturalist. 
Genus Orchestia 
O. agilis, the beach-flea. These little crustaceans exist in countless 
numbers under the masses of sea-wrackon the beach. When disturbed they 
jump about with great agility by means of the last 
three pairs of abdominal feet, which are adapted 
to this purpose. In color the animal is brown 
and much resembles the decaying seaweeds 
among which it lives and upon which it probably 
feeds. The antennules are short, the antenne 
long, on two long, jointed bases. The second : 
pair of feet in the males terminate in chele. The last abdominal appen- 
dages are stiff and pointed backward. The abdomen is curved under. 
The length of Orchestia is half an inch or less. Some species occur onall - 
beaches. 0. agilis ranges from New Jersey to Greenland. 
Orchestia agilis ; male. 
Genus Talorchestia 
T. longicornis (Talitrus longicornis). This species is similar to 
Orchestia agilis, but is about an inch long when mature and of a paler 
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