520 PROCEEDINGS OF THE NATIONAL RrUSEUM vol. im 



Mastomys natalensis agurensis, new subspecies 



Figure 7,a 



Type: BM No. 28.3.11.54, adult male, skin and skull, from Agur, 

 Nuba Mountain Province, Anglo-Egyptian Sudan. Obtained March 

 8, 1927, by W. Rutledge. 



Specimens Examined: Twelve, all in BM, from: Agur, 2; Jebel Um 

 Dona, 1; Delami, 1; Talodi, 2; Abu Heraz, 1; Nahud, 1; Billing, 2; 

 Nuba Mountains, 2. 



Diagnosis: Upperparts near Buckthorn Brown but slightly inter- 

 mixed with black. Color purest on upper arms, shoulders, and cheeks. 

 Underparts, thighs on inner surfaces, forearm on inner surface, hands, 

 and feet white. Skull relatively large, auditory bullae relatively 

 small, zygomatic arches not widely flaring, dorsal surface rather 

 strongly arched. 



Measurements of the Type Specimen: Length of head and body 

 1 14 ; length of tail 126 ; length of hind foot 23 ; length of ear 18 ; greatest 

 length of skull 31.8; condyloincisive length 29.9; length of anterior 

 palatine foramina 7.5; crown length of upper toothrow 4.6; least 

 interorbital wddth 4.4 ; width of rostrum at level of antorbital foramen 

 4.1 ; length of nasals 12.6; greatest width across zygomatic arches 15.0. 



Comparisons: From M. n. blainei, M. n. agurensis differs in marked- 

 ly lighter color, longer tail, and shorter hind foot. The skulls dijETer in 

 that the zygomata are narrower, auditory bullae smaller, dorsum of 

 skull decidedly more arched, rostrum heavier, and braincase smaller. 



From M. n. macrolepis, M. n. agurensis differs in being smaller and 

 lighter in color. The skull is smaller and of less robust build. 



Compared with M. n. ismailiae, M. n. agurensis is lighter in color and 

 smaller in all external measurements. The skull is smaller in all 

 measurements. 



From M. n. marrensis, M. n. agurensis differs in markedly lighter 

 color and somewhat smaller size. The skull is smaller, the auditory 

 buUae are smaller, and the dorsal surface is somewhat more arched. 



Remarks: The specimen from Abu Heraz is somewhat darker in 

 color than typical agurensis and may represent an intergrade with 

 blainei, but since the specimen is so immature it is not possible to be 

 positive. 



The mammals available from the Nuba Mountain region all present 

 minor differences from sm-rounding named kinds. It is very possible 

 that, if additional collecting were to be done in this area, an area of 

 endemism would be found similar to that of the Jebel Marra. 



