— 2 9 — 



smaller than, or fully as large as, or, in very large spécimens, 

 rarely slightly larger than, the lower one ; the short dorsal keel 

 is less or even feebly developed, but, seen from the side, a very 

 obtuse angle is always visible at the mesial dorsal organ. In 

 the egg-bearing females from the Monaco collection the rostrum 

 is always rather long or long, very or exceedingly narrow; the 

 meros of the elongate legs reaches considerably beyond the tip 

 of the antennular peduncle, the distance between its end and 

 that of the peduncle being as long as, or a little shorter than, 

 the sum of the two distal joints of the last-named appendage. 

 It must, however, be added, that egg-bearing spécimens differ 

 considerably in length from each other and show conspicuous 

 différence in the shape of rostrum : in large females the rostrum 

 is not only absolutely but proportionately longer and narrower 

 than sometimes is the case in smaller spécimens, being very 

 narrowly triangular in the latter but nearly subulate, thus 

 exceedingly narrow, in the former individuals. The largest 

 adult female from the Atlantic measures ig mm in length. — The 

 adult maies are somewhat shorter than the females, and differ 

 in several particulars. The two distal joints of the antennulae are 

 shorter and thicker than in the female, third joint somewhat 

 shorter than second — in the female thèse joints are equal in 

 length — a tuft of sensory hairs originates on the basai part of 

 the outer flagellum, nnally the distance from the end of meros 

 of the elongate legs to the tip of the antennular peduncle is 

 about as long as one of the distal joints of that appendagè, 

 and always conspicuously shorter than the sum of both joints. 

 The front end of the carapace is frequently shaped as a low 

 triangle with its angular apex measuring about 90 0 , but some- 

 times a very short rostral process is found. 



Adult females in the Siboga collection differ from my 

 Atlantic spécimens in being a little more clumsy and in two 

 further particulars. The distance between the end of the meros 

 of the elongate legs and that of the antennular peduncle is only 

 as long as the terminal joint or, at the most, as the sum of the 

 terminal and half of the second joint of this appendage. Ro- 

 strum is never subulate, in some spécimens it is very narrowly 

 triangular as in certain Atlantic individuals, but often it is a 



(42) 



