A NEW FRESH- WATER CRUSTACEAN. 



BY H. GARMAN. 



MANCASELLUS MACROURUS, n. sp. Outline seen from 

 above elongate oval, a trifle widest posteriorly. Terga 

 convex, with an obtuse median ridge. Head excavated in 

 front, with a slight median tooth, and a blunt prominence 

 on each side midway between this and the lateral margin. 

 A deep cleft in the expanded lateral portion of the head 

 separates from the rest a posterior lobe on each side. 

 Eyes opposite these clefts, rounded, prominent. Lateral 

 edges of all the body segments behind the head rounded. 

 Posterior segment very large and wide, a trifle hollowed 

 out above the insertion of the caudal appendages. Most 

 of the segments roughened on each side ot the median ridge, 

 all broadly explanate at the sides. Upper antennae small, 

 about as long as the first four articles of the second pair ; 

 composed of nine segments, the first large, globose, short ; 

 the second cylindrical, about as long as the three follow- 

 ing together ; third about twice as long as the fourth, re- 

 mainder subequal. Second antennae reaching the posterior 

 margin of the fifth body segment when drawn back ; pedi- 

 cel composed of five segments, of which the first three are 

 short, and the remaining two, long and cylindrical ; flagel- 

 lum swollen at base. Mandibles without palpi. First 

 pair of legs of male with hand greatly swollen, oval, shin- 



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