ioó 



the end curved inwards, but I have not seen any similar thing, as these setae show the same 

 shape in P . latifrons as in the species of Euphausia. 



Distribution. Sars stated that his specimens were from the south-east coast of 



Australia, the Arafura Sea and off Mindanao, Philippine-Islands. 



Nematoscelis G. O. Sars. 



This genus is difficult. Sars established 4 species: N. mcgalops, N. microps, N. tcnella 

 and N. rostrata. N. mcgalops is easily distinguished by having the long spines on the elongated 

 pair of legs projecting both from the penultimate and from the last joint, while in all other 

 species hitherto found these spines project only from the last joint. Sars founded his N. tcnella 

 and N. rostrata on half-grown or still younger specimens; in 1905 I cancelled N. rostrata as 

 the young of N. microps and redescribed N. tcnella from adult specimens of both sexes. In 1887 

 Chun established N. Sarsii on a specimen from the Mediterranean, but it is quite impossible 

 from the characters given to guess anything on the relationship of the animal, and if the type 

 does not exist the species ought to be cancelled as unrecognisable. In 1896 Chun established — 

 described and figured — N. mantis on a male taken off Funchal (Madeira); in 1905 I cancelled 

 it as belonging to A T . microps, but in spite of the shape of the eye on Chun's fig. 1 (Taf. XII) 

 this interpretation is wrong: the animal belongs certainly to N. tcnella G. O. Sars, as according 

 to Chun's fig. 8 the proximal process of the copulatory organs has several very conspicuous 

 saw-teeth on the distal part of the inner margin, and the lower antennular flagellum is straight 

 at the base (not curved as in N. gracilis n. sp. ; see below). In 1907 Iixig attempted a revision 

 of the genus, re-establishing N. rostrata G. O. Sars as a valid species, but the characters used 

 by him for separating N. rostrata from N. microps are of no value. 



Later I began to examine the copulatory organs, and then I arrived at the result, that 

 my vast material from the three Oceans comprises 5 species, viz. N. mcgalops G. O. Sars, 

 N. microps G. O. Sars, N. tcnella G. O. Sars and 2 undescribed species closely allied to N. 

 microps \ one of these new species, for which I propose the name N. atlantica, I possess only 

 from the Atlantic, while I have specimens of the other, A T . gracilis, in the "Siboga" collection 

 and from the Pacific. The adult males of all species are easily separated by examining the 

 copulatory organs, while the adult females and especially immature specimens of three of the 

 species (N. microps, JV. atlantica and N. gracilis) are more difficult, and half-grown or still 

 smaller specimens are sometimes impossible to determine with real certainty. - - A general view 

 of the male copulatory organs in this genus is given above on p. 80. 



The "Siboga" collections contains 3 species, N. microps G. O. S., N. gracilis n. sp. and 

 N. tcnella G. O. S. But it may be useful to give an analytical key to the males of all species. 



A. First elongated pair of legs with long spines both from the penul- 

 timate and the last joint. Inner lobe of the copulatory organs with 

 the proximal process much shorter and less thick than the terminal 

 process N. mcgalops G. O. S. 



