1879.] NATURAL SCIENCES OF PHILADELPHIA. 425 



mens collected by Prof. Webster at Beaufort, N. C, Marcou Pass, 

 and Charlotte Harbor, Fla. Only four specimens were obtained, 

 two male and two female. 



Rostrum compressed, not reaching the extremit}^ of the anten- 

 nular peduncles; above arcuate, with seven or eight teeth, the 

 second of which is directly above the insertion of the eyes; an- 

 tennal scale large, extending be}'ond the antennular peduncle, 

 the sides parallel, the extremity obliquely rounded, truncate; 

 first pair of pereiopoda reaching the tip of the antennal scale, 

 the second longer, the fingers of each about as long as the palm, 

 remaining feet bi-unguiculate, all very slender and almost filiform; 

 abdomen between four and five times the length of the carapax ; 

 third segment (and sometimes the fourth also) of the abdomen 

 swollen, fifth short, sixth about the length of the carapax; telson 

 slender, elongate, sides straight, regularly tapering to the acute 

 tip. The female appears to be rather stouter than the male. 

 Length 15.5-20 mm. 



&' 



Section II. Mandibles with a Palpus. 



A. Antennulae biflagellate. 



Genus Pal^emonella Dana. 1 Body not depressed ; rostrum 

 moderate; eyes of medium size; mandibular palpus two-jointed, 

 very short; antennulae biflagellate, one flagellum with the apex 

 bifid ; external maxillipeds slender, pediform. Type Palemonella 

 tenuipes Dana. 



o Genus Hymenocera Latreille. Antennulae biflagellate, one 

 flagellum membranous, dilated, and foliaceous ; first pair of pe- 

 reiopoda very slender, hand minute, second stouter, very broad, 

 hand and dactylus membranous. 



B. Antennulae triflagellate. 



Genus Pal^emon Fabr. 2 Rostrum lamellate, dentate; eves 

 free; mandibles with a three-jointed palpus; external maxilli- 

 peds slender. Type Paleemon squilla (Linne, sp.). 



1 U. S. Expl. Exped. Crust., p. 582. 



2 Leander, Desmarest, Annales Socicte Entomologique de France, vii. p. 

 87, 1849. Bithynis, Philippi, Arcliiv fur Naturgeschiehte, xxvi. pt. 1, pp. 

 161-164 (1860). Macrobrachium, Spence Bate, Proc. Zool. Soc'y London, 

 1868, p. 363. 



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