AMPHTPODA. 



NATATORIA. 



MEGAMCERA SEMISERRATA. 401 



GAMMARIDES. 



MEGAMCERA SEMISERRATA. 



Specific character. Third segment of the pleon having the inferior half of 

 the posterior margin serrated. Eyes oblong. Second pair of gnathopoda 

 having the propodos not broader than the carpus, ovate. Posterior pair of 

 pleopoda with the rami equal. Telson double. 



Length \ inch. 



Megamwra semiserrata. SPENCE BATE, Cat. Amph. Brit. Mus. p. 226, 

 pi. xxxix. fig. 6. 



THIS animal is slender, and has the inferior moiety 

 of the posterior margin of the third segment of the tail 

 serrated. The eyes are small, and more reniform in shape 

 than in any other species of the genus. The superior 

 antennae are half the length of the animal, but the 

 inferior scarcely extend beyond the peduncle of the su- 

 perior. Both pairs of hands are nearly of the same shape, 

 but the second pair are larger than the first, and of a 

 long oval form, having an oblique palm defined by one or 

 two short spines ; the finger is short and serrated upon 

 the inner distal half. The coxae of the anterior four 

 pairs of legs are furnished with a single tooth upon the 

 infero-posterior angle. The last three pairs of legs 

 have the posterior margin of the thighs serrated. The 

 posterior pair of caudal appendages reach far behind 



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