200 DR WALTER M. TATTERSALL ON 



length to the preceding three joints, and slightly longer than the fifth joint. The 

 flagellum is short, about half as long as the fifth joint, composed of three joints, the 

 last joint terminating in a spine. I cannot see any denticulations on the inner margin 

 of the flagellum. The inferior antenna is armed with a few scattered stout setse 

 similar to those which are found on the body, but there are no teeth or spines 

 of any kind. 



The first gnathopods are broken off on both sides. The remaining legs present no 

 special features. 



Only one other South African Arcturid is known, Antarcturus kladophorus, 

 Stebbing (1908). From this species A. ornatus is readily distinguished by the quite 

 different character of the armature of the body, by the shorter and stouter inferior 

 antenna, and by the shorter flagellum to the latter. I know of no species of this group 

 with which A. ornatus can be confused. Spiny and tuberculous forms are common, but 

 no setigerous species have been described. 



The generic position of this form is doubtful. STEBBING (1908) gives a table for 

 the discrimination of genera belonging to this family, based primarily on the number of 

 marsupial plates. KOEHLER (1911) has shown that all the genera of Arcturid^e possess 

 three oostegites, and that therefore this character is useless for generic separation. 

 This discovery increases the difficulty of deciding the generic position of the species of 

 the family. In the general form of the body, A. ornatus approaches Antarcturus and 

 Arcturella, and 1 provisionally refer it to the former genus. It cannot be referred to 

 Arcturina, Koehler, because the second and third thoracic limbs are not robust, 

 but conform to the type met with in Antarcturus. Male specimens are necessary to 

 decide whether it should be referred to the genus Arcturopsis, Koehler. The 

 separation of the epimeral plates would seem to exclude it from the genus Pleuroprion, 

 zur Strassen. 



Tribe ASELLOTA. 



Family JANIRID.-E. 



Genus lais, Bovallius. 



lais pubescens (Dana). 

 1. /mbescens, StebMng, 1900a. 



Scotia. 



Station 118, lat. 51 41' 8., long. 57 51' W. 



A large number of specimens of this curious and interesting commensal Isopod 

 were found in the bottles containing Exosp/iwroina gigas from Port Stanley 

 and Port William, Falkland Isles. They were, presumably, living on the latter 

 species when captured. I have nothing to add to STEBBING'S description of the 

 species. 



(ROY. soc. EDIN. TRANS., VOL. XLIX., 890.) 



