GAMMARIDEA. 955 



Female ?— Length, four lines. Colour, greenish. The flagellum of 

 the superior antennae is slender terete and consists of fifteen to twenty 

 oblong joints, which have a whorl of setae at apex a little longer than 

 the joints, the setae standing very nearly at right angles with the 

 organ. The inferior antennae are about three-fourths as long as the 

 superior; the third and fourth joints are long, the third slightly the 

 longer; the flagellum is hardly longer than this joint; the first joint is 

 acute below at apex. The finger of the anterior hands is articulated 

 with the middle of the apical margin, and the hand is naked or nearly 

 so. The hands of the second pair have the apex slightly prominent; 

 the finger is half as long as the hand ; the hand is naked. The third 

 and fourth pairs are very slender and about equal. The last pair of 

 stylets is longer than the first, and the second pair is not half as long 

 as either. The maxillipeds terminate as usual in a stout and long 

 spine. 



AmphitJioe tenuicornis, Dana, Proc. Amer. Acad. Sci., ii, 215, male; A. (Melitd) in- 

 cequistylis, D., ibid., 214, female. 



Genus MJEBA {Leach), D. 



Gammaro Melitae^we affinis. Styli caudales postici scepius valde elon- 

 gati, ramo uno longo, dltero hrevissimo vel obsoleto. Ejpimerce jparvce. 

 Antennce lmce appendiculatoe. 



Near Gammarus and Melita. Caudal stylets of last pair usually much 

 elongate, one branch long, the other very short or obsolete. Epi- 

 merals small. Superior antennae appendiculate. 



The males in Mcera of Leach, as this genus is characterized by him, 

 have one hand very much larger than the other. We do not regard 

 this character as the prominent distinction, and adopt another one 

 pertaining to the stylets. 



In each of the three species here mentioned, the first four or five 

 joints of the abdomen have the posterior margin more or less dentate. 



JVLeRA VALIDA. 



Gracilis, epirneris angustis. Oculi rotundati. Antennas, tenuissimce • 



242 



