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MARINE INVERTEBRATES 



Gammarus locusta, the scud. 



color. It jumps like the latter, but not so strongly. It is found among 

 the weeds and burrowing in the sand a little below high-water mark. 

 The wet sand is often completely filled with its holes. It can be distin- 

 guished by its very long antennas. Another species,T. megalophthalma, 

 is distinguished by its shorter antennas and very large eyes. Both of 

 these species are grayish in color and closely resemble the sand. Found 

 from Cape Cod to New Jersey. 



GENUS Gammarus 



G. locwsta. The animals of this genus are among the largest of the 

 amphipods. The males are larger than the females, sometimes being 

 one and a half inches long. They 

 are abundant under stones and 

 Fucus at and near low- water 

 mark. Although much larger 

 than the beach-fleas, they other- 

 wise resemble them. They do 

 not jump like the former, but 

 move rapidly, lying -on the side, 

 and in water swim with the back 

 downward. Two pairs of the tho- 

 racic feet are chelate, and three 

 pairs are longer than the others. The feet on the last segments of the 

 abdomen are stiff and turn sharply back, forming a part of the tail, which 

 is used most effectively in locomotion. The antennules and antennae are 

 of about the same length. Several species of Gammarus occur in the same 

 range, all having the same general characteristics ; some have but one 

 pair of chelate feet ; the antennules are usually shorter than the antennas ; 

 the females of all the species have no chelate feet. G. locusta ranges from 

 New Jersey to Greenland. The color is generally reddish- or olive-brown. 

 G. annutatiis is found in the same places, but usually a little higher up 

 on the beach ; it is lighter in color, and has dark bands with red spots 

 on the sides of the abdomen. G. mucronatus occurs from Cape Cod 

 to Florida. Melita nitida is a smaller slate-colored amphipod found in 



some places ; another is Mcera levis, 

 which is whitish, with black eyes. 



GENUS Chelura 



C. terebrans, the boring amphipod. 

 This little crustacean is associated in 

 its work on submerged timber with 

 the isopod Limnoria lignorum. The 

 excavations of the latter are narrow 

 and cylindrical, running down into 

 the wood, while Chelura makes larger 

 burrows in oblique lines near the sur- 

 face, which give the wood the appearance of having been plowed. It 

 is very active and destructive. It feeds upon the wood into which it 

 burrows. Its color is semi-translucent, thickly mottled above with pink. 



Clielura terebrans, the boring amphipod. 



