I09 



in fig. 2 i this crest is less developed. The lateral margin of the carapace with a conspicuous, 

 acute denticle a little before the posterior end. The two figures show the gradual development 

 of the sections of the eyes; in the smallest specimen (fig. 2k) the lower section is several times 

 larger than the upper, while in the other specimen (fig. 2 i) the difference between the sections 

 is much lesser, the upper section being considerably more developed than in the younger stage. 

 The small specimen has only 4 spines on the terminal joint of the long legs, while 7 are found 

 in the adults. Finally the two figures and fig. 2 c — an adult female — show the gradual 

 reduction of the spiniform process on the outer distal angle of first antennular joint. 



Remarks. — The "Challenger" specimen from the Pacific preserved in the British 

 Museum is the "type" of Sars, and is represented by him in fig. i, the main figure. The 

 specimens from the "Siboga" belong unquestionably to the same species as that type, but without 

 a renewed e.xamination I cannot decide whether the "Challenger" specimen from the Atlantic 

 belongs to this species or to N. atlantica n. sp. As already stated, N. microps in my Monaco- 

 papers comprises both species, and sometimes I have numerous specimens of both from the 

 same station. The males of the two species are easily distinguished by their copulatory organs, 

 and both males and especially the females by the feature that the eyes in N. microps are 

 conspicuously larger than in N. atlantica. From the area explored by the "Siboga" and from 

 the Pacific I have seen no specimens of N. atlantica but numerous specimens of A^. microps., 

 and these specimens agree completely with each other and with specimens from the Atlantic in 

 the size of the eyes and the relative length of the processes on the copulatory organs, but 

 they show much variability in length and shape of the rostrum in both sexes, and while a 

 good deal of this variation is, as already stated, purely individual, still some of it seems to be 

 local variation. Thus the rostrum in the males from the Pacific is longer than in any specimen 

 from the "Siboga", while in most, but not in all, males from the North Atlantic the rostrum 

 is nearly wanting, being still considerably more reduced than in the specimen shown in fig. 2 a. 

 As already stated, the rostrum of the adult females varies much as to breadth in the "Siboga" 

 specimens, but it is less variable in my specimens from the Pacific, while in females trom the 

 Atlantic it is extremely slender. 



Distribution. — As stated I have this species both from the Atlantic and the Pacific, 

 but a more special account must be postponed, and nearly all statements on occurrence in the 

 literature are valueless, as this species has been confounded with two other species. 



16. Nematoscelis gracilis n. sp. PL XV, figs. 3« — 3_^. 



Stat. 118. July 13. Lat. i°38'N., long. I24°28'.2E. Hensen vertical net, from 900 m. to 



surface. 4 immature or even small specimens. (Probably this species). 

 Stat. 128. July 22. Lat. 4°27'N., long. 125° 25'./ E. 1645 m. Hensen vertical net, from 700 m. 



to surface. 2 specimens (cT and 9)- 

 Stat. 141. August 5. Lat. i°o'.4S., long. I27°25'.3E. 1950 m. Hensen vertical net, from 



1 500 m. to surface. 4 specimens (Q and immature specimens). 

 Stat. 143. August 7. Lat. i°4'.5 S., long. I27°52'.6E. 1454 m. HENSEN vertical net, from 



1000 m. to surface. 4 specimens (adult 9 and subadult specimens). 

 Stat. 148. August 10. Lat. 0° i/'.e S., long. 129° 14'.$ E. 1855 m. HensEN vertical net, from 



1000 m. to surface. 12 specimens (cT, 9 and immature specimens). 



