NO. 17 NliW SPECIES OF EAST AFRICAN RODENTS — HELLER I3 



Lophuromys is scarcely perceptible on the surface of the posterior 

 portion of the ramus. This genus has the external characters of 

 Lophuromys with the palatal skull formation of Aconiys and dis- 

 tinctive projecting incisors and marked mandibular characters. 



ACOMYS HYSTRELLA, new species 



Gray-backed Spiny Mouse 



Type from Nimule, Uganda; adult female, number 164821, U. S. 

 Nat. Mus. ; collected by J. Alden Loring, February 4, 1910 ; original 

 number, 8929. 



Characters. — Size large ; tail three-fourths head and body ; dorsal 

 coloration drab gray with fulvous sides ; nasal bones short. 



Coloration. — Median dorsal region from the snout to the base of 

 the tail drab-gray, this color merging gradually into the fulvous 

 of the sides ; fulvous of cheeks, lower sides, and legs sharply defined 

 against the white of the under parts. Spinous hair of sides annu- 

 lated, the extreme tip seal brown, succeeded by a broad band of 

 fulvous, which is followed by cinereous gray to the base ; this annu- 

 lation is not perceptible in the darker spines of the back, the sub- 

 terminal band of drab-gray being nearly as dark as the tips. Feet 

 white. A small white spot below the ear. Ears smoky-brown 

 clothed with a mixture of minute brownish and silvery hairs. Tail 

 sharply bicolor; above lighter gray than the back, below whitish. 

 Under parts, including upper lips and feet, white, the hair wliite to 

 the roots. 



Measurements. — Head and body, iii mm.; tail, 81 ; hind foot, 16; 

 ear, 15. Skull: greatest length, 28.3; basilar length, 22; zygomatic 

 breadth, 13.2; nasals, 10.5x3.5; interorbital constriction, 5; length 

 of palatine foramina, 6.7 ; length of upper toothrow, 4.5. 



From the Somali species, mullah, this species differs in its smaller 

 size, more fulvous sides, and shorter tail and nasal bones. The ful- 

 vous sides also distinguish it from the grayish cahirinus of Egypt, 

 from which it further differs by larger skull and acutely pointed 

 mesopterygoid fossa and smaller bullae. 



DASYMYS ORTHOS, new species 



Nyanza Swamp Rat 



Type from Butiaba, Albert Nyanza, Uganda ; adult male, number 

 164824, U. S. Nat. Mus. : collected by J. Alden Loring, January i, 

 1910; original number, 8601. 



