lO 



The pleopods are nearly fully formed but their rami bear only a few very short seta;. 



The peduncle of the uropods (PI. II, fig. 14) is about equal in length to the last somite 

 and bears about seven long and six short spines internally. The exopod is about two-thirds 

 the length of the peduncle, rather broad, the proximal segment about -/s the length of the 

 distal along the outer margin. There are some short spinules along the outer edge and long 

 setse on the inner edge and at the tip. 



The endopod is a very little shorter than the exopod, its proximal a little longer than 

 its distal segment and much stouter. On the inner edge of the proximal segment are nine spines, 

 the distal one rather long. The distal segment has eight short spines internally and three longer 

 ones at the tip. 



Occurrence. Station 211, 1158 metres, i specimen. . 



Remarks. The specimen described above agrees with the genus Bathyaiina in 

 possessing exopods on all except the last thoracic legs, the basis of the third maxilliped 

 strongly produced distally, and a serrated dorsal crest with a double row of alternating teeth 

 on the carapace. 



Comparing it with the summary which I have given elsewhere (Fisheries, Ireland, Sci. 

 Invest., 1904, I, (1905) p. 18) of the characters of the two species already known, B. 

 elongata Hansen, and B. brevirostris (Norman), the following appear to be the chief diagnostic 

 features of the new species : — Carapace more than twice as long as deep ; pseudorostrum 

 one-fifth of length of carapace, its upper margin horizontal, without serrations; basis of third 

 maxillipeds with a few teeth ; second legs with ischium distinct ; peduncle of uropods longer 

 by one-half than the subequal rami. 



Family Nannast.^cidae. 



Nannastacus. 



Although only a small number of species belonging to this genus have been described 

 hitherto, the Siboga collections and others which are now in course of examination indicate 

 that the genus plays an important part in tropical seas, and that, in the plankton of inshore 

 waters, the numbers of individuals and of species are often considerable. As a rule however, 

 only the males are obtained in this way, the females haunting the bottom and being more 

 rarely captured by the townet. Many of the species are apparently very closely allied, and 

 only to be discriminated with difficulty at least in the absence of females. It is on this account 

 that Ihave not ventured to determine more than a part of the Siboga material of this genus. 

 In addition to the species named below, representatives of at least four others were obtained 

 the consideration of which may be deferred until further material from the neighbouring regions 

 has been worked through. 



