798 CRUSTACEA. 



outline. The eyes consist of six facets. None of the thoracic segments 

 are as long as broad ; the fifth and sixth are somewhat the longest, 

 and are much longer than the seventh, which is twice as broad as 

 long. The segments of the abdomen are of nearly equal length, the 

 last not being longer than the preceding. The stylets consist of a 

 rather stout basal joint and five more slender joints ; they are some- 

 what hairy. The legs, excepting the first pair, terminate in a claw, 

 which is short, excepting in the second pair ; in this the claw is 

 slender and nearly as long as preceding joint, upon which it closes. 

 First pair of legs thrown forward either side of head. The thumb 

 has a depression in the inner margin near its base, and another near 

 its apex ; to the former a tooth in the finger corresponds ; and into 

 the latter the extremity of the finger closes; the intermediate por- 

 tion of both thumb and finger is finely denticulated; the second 

 joint of the leg is compressed near its base. The superior antennas 

 decrease in diameter from base to apex. The second pair has a two- 

 jointed base and a four-jointed extremity. 



This species is near the Tanais dubius of Kroyer (Tidsskr. Heft., 

 2, 1842) ; but it is peculiar in having the last of the six abdominal 

 segments not longer than the preceding, and also slightly apiculate 

 behind. 



Tanais brasiliensis, Dana, Amer. J. Sci. [2], yiii. 425. 



Genus PARATANAIS, Dana. 



Tanai pediblts anticis breviter et crassd chelatis antennisque Imis fla- 

 gello non confectis similis. Styli caudales biramei, ramis inwquis, uno 

 vel pluribus articulis instruztis. 



Like Tanais in having the anterior feet stout chelate and short, and 

 the antennae without a flagellum. Caudal stylets two-branched, 

 branches unequal, one or many-jointed. 



This genus is separated from Tanais by only a single character; 

 yet the distinction may be convenient. The accessory branch of 

 these stylets may exist in the preceding Brazilian species ; and, if so, 



