504 Mr. 0. Thomas on 



This squirrel is very like the Cali S. similis, of which four 

 topotypes, also collected by Mr. Palmer, are in the Museum 

 collection. But that is a comparatively highland form 

 (SSOO'-GOOO'), and the specimens show a uniformly oliva- 

 ceous tint, recognizably distinct from the brown colour of the 

 coast animal. 



(Ecomys rex, sp. n. 



A large species, with much developed supraorbital ridges. 



Size equalling that of the largest known species, (E. catha- 

 rince. General appearance very much as in that animal. 

 Colour above rich tawny rufous, approaching ferruginous, 

 considerably blackened on the posterior back, bright and 

 clear on the nape and flanks. Under surface dull whitish, 

 not very sharply defined laterally, the hairs pale slaty for 

 their basal two-thirds. Head like body, without darker 

 markings. Proectote of ear blackish. Forearms like sides; 

 hands brown on metacarpus, the fingers abruptly white; hind 

 feet proportionally very short, brown on the metatarsus, 

 white along the hallucal edge and on the toes. Tail well- 

 haired but not tufted ; uniformly dark brown as usual. 

 Mammse 2—2 = 8. 



Skull broadly built and remarkable for the great develop- 

 ment of the supraorbital ridges, which form broad ledges over 

 the orbits, develop marked angular postorbital projections, 

 and pass backwards across the parietals to the outer corners 

 of the interparietal. Nasals narrow. Interorbital region 

 concave between the ridges. Anterior plate of zygoma-root 

 projected forward, as in (E. catharince. Palatal foramina of 

 medium length. 



Dimensions of the type (measured in skin) : — 



Head and body 152 mm. ; tail 158 ; hind foot (wet) 26 

 ear (wet) 16. 



Skull : greatest length 33 ; basilar length 26*3 ; nasals 11 

 interorbital breadth 6 ; breadth across postorbital processes 

 13'5 ; breadth of brain-case 15"5 ; palatilar length 14*6 

 palatal foramina 6'4; upper molar series 5*5. 



Bab. R. Supinaam, Lower Essequibo, Demerara. 



Type. Old female. B.M. no. 10. 9. 29. 17. Collected by 

 Cozier and presented by F. V. McConnell, Esq. 



This handsome species is readily distinguishable from all 

 others by the great development of its supraorbital ridges 

 and postorbital projections, which recall those found in 

 Tylomys and Lenomys. lis nearest relation would seem to be 

 the South-Brazilian (E. catharince, which shares with it the 



