378 Mr. 0. Thonia? on new Species of 



LT. — Neio Species o/CEcorays and M\vmos& from 

 Amazonia. By Oldfield ThOMAS. 



(Published by permission of the Trustees of the British Museum.) 



Among some Amazonian mammals sent to us for determina- 

 tion by Fraulein Dr. E. Snethlage, of tlie Goeldi Museum, 

 Para, there are examples of a new (Ecomys and a new 

 Marmosa, which are here described. The tvpg specimens 

 have been generously ceded to the British Museum by tiie 

 authorities at Para. 



(Ecomys tapajinus, sp. n. 



A large species of a rich tawny-rufous colour. 



Size about as in the larger members of the gioup, marmo- 

 sums, rohertl, and mamorce. General colour brightest of 

 all, a rich tawny or cinnamon-rufous colour, about equal to 

 the brightest members of the genus Nyctomys; this colour is 

 browner on the head and fore back, richer on the rump and 

 hips, where it nearly matches Ridgway's ''tawny," but is 

 brighter and glossier. Under surface white, the hairs of the 

 throat, chest, narrow middle line of belly, and whole of 

 inguinal region white to the roots, tho?e of the side of the 

 belly slaty grey basally; but none the less the passage from 

 the tawny colour of the flanks and the white of the belly is 

 nearly as sharply defined as in (E. roherti, not gradual as in 

 martnosurus. Hands and feet greyish white. Tail, as usual, 

 long, uniformly brown, finely pencilled. 



Skull most like that of (E. roherti, but rather more heavily 

 built; outer plate of zygoma-root narrower; palatal fora- 

 mina longer, tooth-row shorter. 



Dimensions of the type (measured in flesh) : — 



Head and body 126 mm. ; tail 158; hind foot 25; ear 17. 



Skull : tip of nasals to front corner of interparietal 28"6 ; 

 zyo-omatic breadth 16 ; nasals 11"8 ; interorbital breadth 5*9 ; 

 zygomatic plate 28 ; diastema 9"2 ; palatal foramina 5"8 x 3 ; 

 length of upper molar series 4*7. 



JIah. Santa Rosa, R. Tamauchim, right bank of the Upper 

 Tapajoz R. 



Type. Old female. B M. no. 9. 3. 9. 9. Original num- 

 ber 21. Collected by Friialein Dr. E. Snethlage. 



This species may be readily distinguished from the other 



