142 Mr. O. Thomas on 



more violaceous hue, and by the possession of a large oliva- 

 ceous brown band occupying the upper end of the cell and 

 reaching to the black apical border. The lobe is much 

 smaller and black. 



On the underside the ground-colour is much as in T. be- 

 renis, but the transverse lines are placed further inwards from 

 the margins and are much straighten There are no faint 

 lines closing the cells of both wings, as in T. berenis, and the 

 orange patches at the anal angle of the hind wing are paler, 

 more extensive, and not separated by the submedian inter- 

 space, as in T. berenis. The black lobe is crowned with 

 shining silvery-blue scales. 



$ . — Upperside differs from male only by the disk of the 

 fore wing being of a slightly paler blue, the apex being less 

 broadly black, and by the total absence of the olivaceous 

 brand. 



On the underside the dark transverse line is more con- 

 spicuous and more distinctly edged outwards with whitish 

 than in the male. 



Head, thorax, and abdomen bluish above, pearly white 

 below ; legs white-spotted ; antennae minutely white-spotted. 



Expanse If inch. 



Hab. Kina Balu, Borneo (Mus. Druce). 



Distinguished at once from all others of the group by the 

 large brand in the male, which may necessitate the erection of 

 a new genus to contain it. 



XVII. — Two new Mammals from South America. 

 By Oldfield Thomas. 



Oryzomys oniscus, sp. n. 



A medium-sized species allied to 0. intermedins and 

 0. laticeps. 



Size about as in 0. intermedins, therefore larger than in 

 0. laticeps. Fur close and rather short; hairs of back barely 

 10 mm. in length. General colour of upper surface dark 

 greyish tinged with buffy, the resulting tone being rather 

 paler than Kidgway's " bistre " and very near that of certain 

 of the darker forms of the laticeps group, e. g. 0. perenensis, 

 Allen. Median area of back noticeably darker than rest. 

 Sides rather, but not conspicuously, more buffy. Whole of 

 under surface and inner sides of limbs greyish white (" grey 



