162 Bulletin, Vanderhilt Manne Museum, Vol. Ill 



rostrum rounded over the ocular lobes and then retreating in a broad 

 curve to unite with the lateral margin, which is sinuate, its postlateral 

 angle being rounded and is produced on the outer posterior half of 

 each side beyond the median posterior margin which is relatively 

 straight. The entire animal is decidedly compressed laterally, the 

 abdominal segments are not carinated, but show this compression pro- 

 nouncedly. The first five segments are approximately subequal in 

 length ; the sixth segment is somewhat longer. The first four segments 

 have the epimera broad and evenly rounded ; the fifth segment has the 

 epimera rounded also but produced on the posterior distal angle to an 

 acute point, the anterior epimeral margin being rounded but much 

 longer than the posterior margin ; the sixth segment has the shape 

 typical of members of this genus. The telson is convex on the upper 

 surface, tapers distally and has the narrow, posterior end produced 

 to a shallow triangle. There are two submedian pairs of spines on the 

 telson, the anterior pair being approximately midway the length of 

 the telson and the second pair being a little posterior to halfway the 

 distance between the first pair and the telson. The rhipidura have 

 a short, strong base which is produced distally to an acute point that 

 projects over the outer blade ; the lateral margins of the peduncle are 

 finely, irregularly serrated. The inner blade is oval, nearly half as 

 wide as long, traversed by an approximately median ridge which is set 

 with long setae ; the lateral and distal margins of the blade are fringed 

 with setae. The outer blade is subequal to the inner but has the outer 

 margin straight, a trifle thicker than the rest of the blade ; the distal 

 third of the blade is obliquely articulated with the proximal two- 

 thirds, this line of segmentation being accentuated by a fringe of short 

 setae, and at the outer margin by a spine which is the produced apex 

 of the outer margin of the proximal portion. The rounded distal por- 

 tion is heavily fringed with setae. 



The antennulae consist of five peduncular articles and a biramose 

 flagellum, the shorter, upper branch being composed of about 24 taper- 

 ing articles, the median half of which bear a very prominent, curled 

 brush of close-set setae. The longer, inferior placed flagellum consists 

 of about 62 annulations and extends slightly beyond the distal end 

 of the first periaepod. 



The antennae have a short, stout, basal article which bears on its 

 upper distal margin a sharp, triangular acicule that reaches to the 

 base of the flagellum of the antennulae ; the second article arises be- 

 neath the acicule and is cylindrical and about one-fourth longer than 



