GENUS OF TEKKESTRIAL ISOPODA. 447 



marked, especially in the full-grown males ; two o£ my male specimens are 

 apparently not quite fully grown and have the antennae considerably more 

 slender than is shown in fig. 27, and more approaching the conditions found 

 in the female, though much stouter ; the prominence of the tubercles on the 

 perseon is also less marked in the immature males. 



I think there can be no doubt that D. magnifica, Budde-Lund, and 

 D. rohusta, Budde-Lund, are synonyms of this species. Budde-Lund estab- 

 lished these two species on three specimens from the Auckland Islands in 

 the Dresden Museum ; of D. magnifica he had only one imperfect specimen, 

 and states that it is perhaps the same as D. aucklandice. Of D. rohusta he 

 had one male and one female, and apparently based the specific distinction 

 largely on the characters of the male, the difi"erences of which from the 

 female had not previously been fully pointed out. In his original de- 

 scription, Mr. Thomson, by an error, interchanged the sexes and described 

 the female as being provided with the stout obtuse spines. 



The specific diagnosis given above may be supplemented by the following 

 more detailed description of the appendages : — 



Antennules (fig. 26) small but noticeable, first joint as long as the second 

 but shorter, third about half as long as the second, narrower, and tapering ; 

 all covered with fine short hairs, two or three minute olfactory setae near the 

 end of the third. 



The antennae in the fully grown males (fig. 27) are particularly broad and 

 powerful, all the joints being broadened and having the surface uneven, as 

 shown in the figure ; the fifth joint is about the same length as the fourth 

 or only slightly longer, and lies nearly at right angles to it, the outer surface 

 of the fourth being hollowed out towards the extremity to receive it ; the 

 flagellum is about half as long as the fifth joint and shows three subequal 

 joints, each broader than long, the very small fourth joint being almost 

 concealed in the fine downy hairs which cover the flagellum and the terminal 

 portion of the peduncle. 



In the female the antennae (fig. 28) are very much more slender, but show 

 the same proportions, except that the third joint of the flagellum is longer 

 than either of the first two, which are subequal and about as broad as long ; 

 the fourth joint is small, though readily noticeable ; the fine hairs found in 

 the male are hardly represented. 



In immature males the antennae tend to resemble those of the female. 



Upper lip with extremity roundly truncate. 



The mandibles are large and strongly chitinised, of the same type as in 

 Oniscus. In the left mandible (fig. 30) the cutting part is composed of two 

 strong teeth somewhat rounded and dark brown in colour, within it lies the 

 accessory appendage also composed of two strongly chitinised teeth, brown in 

 colour, and bearing at its base a membranous, hairy lappet densely fringed 

 with setae ; this is followed by a single " penicil," and then by the brush-like 



