1208 THE VOYAGE OF H.M.S. CHALLENGED. 



length, then converging to a broadly rounded apex, with a setule on either side ; each 

 lateral margin carries a small seta and setule where the convergence begins, and there 

 are two setae and a setule upon the surface not far from each straight lateral margin. 



Length, — The specimen, in the position figured, measured, from the front of the head 

 to the extremity of the uropods, half an inch. 



Locality. — Station 161, off Melbourne, April 1, 1874; depth, 33 fathoms; bottom, 

 sand. One specimen, female, with the eggs in a forward state of development. 



Remarks. — The specific name is given in honour of the distinguished founder of the 

 genus Icilius, with a view also to call attention to the resemblance between this species 

 and the type-species Icilius ellipticus. From Icilius australis, Haswell, this species is 

 distinguished by the produced dorsal point of the seventh peraeon-segment and the first 

 two pleon-segments, by the length of the hand in the first peraeopods, and other 

 particulars. In regard to the third uropods, Mr. Haswell says, " Inner ramus of sixth 

 pleopoda foliaceous, outer small, long ovate." The figure 1 of these uropods would in 

 some degree correspond with the third uropods of the present species, if the figure of 

 those appendages in PI. CXXXIII. were reversed and the outer ramus thus made the 

 inner, with a minute outer ramus supplied ; but the uropods in my figure are, I think, 

 drawn in their natural position, and the cavity in the produced end of the peduncle suggests 

 the attachment of something more than a minute ramus. 



From Dana's Icilius ellipticus, two lines long, " brought up on corallines in thirty- 

 one fathoms" at Balabac Passage, north of Borneo, the present species differs in not 

 having a produced point on the third pleon-segment, in having the head less produced in 

 front and at the sides, the maxillipeds much more strongly unguiculate, if this may be 

 judged from the fact that Dana's figure of the maxillipeds does not show a nail at all. 

 Dana regards the upper antennas as " non-appendiculatae " ; but it is possible that he over- 

 looked the small secondary flagellum, or that it was accidentally missing. He describes 

 the second joint of the upper antennae as " a little longer than third," and figures it in 

 accordance with the description ; he figures the second and third joints of the mandibular 

 palp as subequal, and gives only two setae to the inner plate of the first maxilla. Of the 

 uropods he says, "The three pairs of stylets are rather long, and extend back some 

 distance. The branches of the last pair are quite unequal." In his figure these branches 

 are indistinct, the inner shorter than the outer, but not minute. 



Genus Chosroes, n. gen. 

 Near to Icilius. 



Tipper Antennse without secondary appendage. 

 The third joint of the mandibular palp longer than the second. 



1 Catalogue of the Australian Stalk- aud Sessile-eyed Crustacea, pi. iv. fig. 4, 1882. 



