, S4 DISCOVERY REPORTS 



Description. Carapace very short anteriorly with lateral margins of the short rostrum meeting 

 in a bluntly rounded right angle, not covering even the base of the eyestalks (Fig. 36A). Antennular 

 peduncle showing marked sexual dimorphism. In the female the peduncle is slender; the projection 

 from the outer distal angle of the first segment is nearly twice as long as the outer margin of the second 

 segment; third segment armed with five very long plumose setae along its inner margin and with 

 a group of 4-5 even longer setae on the inner distal angle. The plumes on these setae are particularly 



Fig. 36. Mysidetes dimorpha sp.n. A, anterior end of male in dorsal view, x 16; B, right antennular peduncle of male, x 18; 

 C, right antennular peduncle of female, x 18; D, right antenna, x 16; E, seventh thoracic appendage of male, x 16; F, endo- 

 pod of eighth thoracic appendage of male, x 16; G, endopod of seventh thoracic appendage of female, x 16; H, left uropod, 

 x 16; J, telson, x 16. 



long and conspicuous. Peduncle in the male more robust and the projection from the first segment 

 relatively shorter than in the female ; in immature males there are a few plumose setae on the inner 

 margin of the third segment, but they are smaller than in the female and I can find none in adult 

 males with well-developed antennular brushes (Fig. 36 B, C). Antennal scale small and narrow, 

 extending for about one-sixth of its length beyond the antennular peduncle ; nearly six times as long 

 as broad; peduncle two-thirds as long and equal in breadth to the scale; dorsal spine on the outer 

 distal margin of the sympod longer than the ventral spine, broad at its base and then markedly con- 

 cave on its inner margin and acutely pointed. This spine has the same shape in all the specimens I have 

 examined (Fig. 36A, D). Eyes moderately large, dorso-ventrally compressed, set well apart, cornea 



