On a new Marmoset from the Lower Amazons. 263 
Hab. Doormanpad-bivak (W. C. van Heurn). 
Type: Female. B.M. no. 22.2. 2.74. Original num- 
ber 12. 
Sminthopsis rufigents, sp. 0. 
A greyish species with conspicuously red cheeks, as in the 
much larger S. virginie of Queensland. 
Head and body 91 mm.; tail 102; hind foot 21:3. 
Skull 26:5. 
Hab, Aru Islands. 
Type. Female in spirit. B.M, no. 22. 2. 2. 76. Original 
number XX, 
AXXXIL—A new Marmoset from the Lower Amazons. 
By OLpFigeLpD THOMAS. 
(Published by permission of the Trustees of the British Museum.) 
AN examination of the Museum specimens of Mystaa ursulus 
shows that those from the west side of the Tocantins River 
are definably different trom those round Paré itself. 
The new one may be called :— 
Mystax ursulus umbratus, subsp. n. 
Similar in essential characters to Pardé ursulus, but darker 
throughout, the black shoulder-mantle extending further 
down the back—to halfway between shoulders and thighs— 
and the mottled part of the body grizzled finely with dull 
ochraceous instead of coarsely with buffy. 
Dimensions of the type (measured in the flesh) :— 
Head and body 230 mm.; tail 352; hind foot 68; 
_ ear 80. 
Skull: greatest length 48°5; basal length 35; zygomatic 
breadth 34. 
Hab. Lower Amazons west of the main Tocantins River ; 
type from Cameta. 
Type. Old female. B.M. no. 11.4. 28.4. Original 
number 31. Collected 20th January, 1911, by Friulein 
Dr. HE. Snethlage. Presented by the Goeldi Museum, Pard. 
Ann. & Mag. N. Hist. Ser. 9. Vol. ix. 18 
