The two anterior pairs of thoracic legs agree comple- 

 tely with each other in thickness, length of the joints and 

 their long, fine and plumose setae. The exopod of sixth 

 pair of legs is normally developed as to shape, division 

 and setae; in the adult males an endopod is quite wanting, 

 while in adult females the endopod is articulated in the 

 usual way to the broad inner distal part of second joint of 

 the leg, and this endopod is unjointed, reaching either to 

 the end of the long proximal joint of the exopod or some- 

 what beyond that end to the middle of the setiferous part 

 of the exopod. The exopod of seventh pair of legs is 

 somewhat styliform, naked ; an endopod is wanting in 

 both sexes. Furthermore the antennulae in the adult males 

 have the peduncles quite dissimilar from those in the 

 females and besides differing much from those in any 

 other species of the order ; they may be described here, 

 and the left male peduncle, seen from the outer side, has 

 been figured by G. O. Sars (/5, PI. i, Fig. i5). The first 

 joint of the antennula has towards the inner margin a high, 

 compressed lobe directed more in the longitudinal than 

 in the transverse direction, and along its upper subhori- 

 zontal margin furnished with a close row of long, some- 

 what curved spines. The second joint is thick, with the 

 upper outer distal angle produced in a long, protruding, 

 sinuate, somewhat slender process, while at the upper 

 inner angle one finds a compressed, moderately short 

 process directed essentially forwards and with a row of 

 fine and long setae along its terminal margin. Third joint 

 is slender at the base, but more distally with a very high, 

 long, dorsally rounded upper keel. It may be added that 

 the terminal process of the copulatory organs has its major 

 distal part flattened and rolled up as a long tube with a 

 split along its posterior side. 



Thysanoëssa neglecta Kr. has nearly the same distri- 

 bution in the North Atlantic and the Arctic as Rhoda 

 inermis, but it is not known from the North Pacific; it is 

 on the whole less common than R. inermis, the great 



(210) 



