the liiver Supiimam, Demerara. 1S7 



its allies by its rich rufous colour. It is probably a Giiianaii 

 rejiresentative of the Brazilian 0. intermedins^ Leche, but is 

 more brightly colnurcd. 



I have nainel it in honour of the donor of the collection, 

 ]^Ir. F. V. iMc( 'onnell, to whom the National Museum oucrf 

 not only this but many other valuable donations. 



11. Oryzomys sp. 

 Four. 

 0. huiceps group. 



12. CEconiys guta7ur, sp. n. 



Eight. 



A large species, the hairs of the belly grey-based. 



General characters very much as in (E. marmosurus. Size 

 rather less than in that species, the feet noticeably shorter. 

 Colour above between " tawny " and " clay-colour/' distinctly 

 darker and more brownish than in CE. marmosurus. Under 

 surface dull buffy whitish, the bases of the hairs, except just 

 on the chin and throat, slaty grey, even down the centre line 

 of the belly ; laterally the line of demarcation is sharj^er than 

 in marmosurus^ less sharp than in tapajinus ; a dull buffy line 

 along the lower edge of the colour of the flanks. Hands and 

 feet pale brown, the tine hairs with a silvery gloss. Tail 

 uniform dark brown above and below, the hairy part at its 

 base less than in Ql!. viarmosurus. 



Skull and teeth as in CE. marntosnrus. 



Dimensions of the type (measured in skin) : — 



Head and body 115 mm.; fail 155; hind toot 2G ; ear 16. 



Skull: greatest length l\'2'7 ; zygomatic breadih 17-?; 

 palatal foramina 5'7 ; upper molar series 4'9. 



Type. Adult female. B.M. no. 10. 5. 4. 23. 



The three large species of (Ecomys from N.E. South 

 America, (E. marmosurus^ tapajinus, and the present one, are 

 all very similar in size and cranial characters, but are distin- 

 guishable by the colour of the under surface. In (E. marmo~ 

 tsurus this passes (piite gradually into the colour of the sides, 

 without line of demarcation, and the hairs of the middle line 

 of chest and belly arc white to their bases. In (E. tapojinus 

 all the hairs below are completely white, except just along the 

 sides of the belly, and there is a very sharply defined lateral 

 line of demarcation. In (E. guiaucB i\\\ the hairs below are 

 slate-based and the lateral line is of an intermediate degree 

 of definition. 



