1276 



CRUSTACEA. 







Thorax not deflexed, nearly straight and in same line with abdomen. 

 Abdomen stout furcate at extremity, with no setae at apex. Branches 

 of posterior antenna three-jointed. Shell rounded behind. 



The abrupt downward bend of the thorax of Polyphemus and 

 Evadne is one of their most striking characteristics, and in Poly- 

 phemus the abdomen is quite slender, and takes again the longitu- 

 dinal position. But in Pleopis, the whole is nearly straight and stout. 

 The head is very large and occupied with eyes, as in other Polyphe- 

 midge j and there is a suture separating it from the following part. 

 The legs of the second pair were terete; four joints were observed, an 

 oblong basal, and the following part, but slightly longer, consisting of 

 a long joint and two minute apical, and bearing a few longish setaa. 

 The legs of the fourth pair were much shorter and rather stouter. 

 The three joints of the terminal portion of the leg were nearly equal 

 in length ; their setae were about as long as in the second pair. The 

 shell is very tumid behind and subglobose, instead of being pointed as 

 in Evadne. 



The name of the genus, from *7*«,futt, and w +, eye, alludes to the 

 large head filled with eyes. 



Pleopis brevicaudis. 



Caput oblongum, conoid eum, corpore postico parce brevius, antice latins 

 et subgloboswn. Antennce oblongce, basi crasso, ramis dmbus sub- 

 cequis, 2>-articulatis, parce setigeris. Pedes crassi. Abdomen breve et 

 crassum, apice parce exsertum, furcatum, acutum. 



Head oblong conoid, largest and globular anteriorly, but slightly 

 shorter than body. Antennas oblong, base stout; branches two, 

 subequal, three-jointed, sparingly setigerous. Abdomen short and 

 stout, tip but slightly exsert, furcate and acute. 



Plate 89, ^g. 8 a, lateral view of animal, enlarged ; b, second pair 

 of feet ; c, fourth pair of feet. 



In the Atlantic, latitude 41° south, longitude 62° west, near Bio 

 Negro. Collected, January 25, 1839. 



