— 5o — 



The female N. megalops has a very long and thin 

 rostral process which is wanting in the male. The female 

 of N. difficilis has a rostrum shaped as in the other species, 

 while the three males differ strongly from each other in 

 this respect ; in one male the rostrum is shaped as in 

 the female, in another only a short triangular projection 

 is found completely as in the male of A T . megalops, while 

 in the third specimen the end of the triangle is a little pro- 

 duced, thus showing a quite short, slender process. 



The largest specimen of A 7 , difficilis in an immature 

 male, 21 mm. long. — This species inhabits the northern 

 temperate East Pacific. 



Group B. 



This group comprises four species : N. atlantica 

 H. J. H., N. mi crops G. O. S., N. gracilis H. J. H. and 

 N. tenella G. O. S. The « Siboga » report contains a suffi- 

 cient account of these species, together with notes on 

 synonymy, etc. 



Netomabrachion Calm. 



To Caiman's description a few remarks may be added. 

 Eyes divided into two areas, the upper area broader 

 than the lower. Antennular peduncles similar in both 

 sexes, their two distal joints at least somewhat robust. 

 Maxiilulae with or without pseudexopod. Sixth pair of 

 thoracic legs with full number of joints in the endopod of 

 both sexes. Copulatory organs with all five processes 

 typically found in Thysanopoda well developed. 



By most of these characters the genus differs conside- 

 rably from the other genera with one pair or two pairs of 

 elongate legs. The genus comprises 3 species, all nearly of 

 the same size, measuring at most 2 1-23 mm. The follow- 

 ing key contains the most important characters. 



a. Frontal plate obtuse, without rostral process. Eyes 

 dark brownish ; upper section more than twice as 



