478 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loe 



Greatest length 35.2; greatest width across zygomatic arches 19.5; 

 length of nasals 8.9; crown length of upi)er tootlirow 5.7. 



Remarks: It is apparent that tliis small chipmimk-likc squirrel has 

 reached tlie northern limit of its distribution where the Congo forest 

 extends into tlie Sudan. These animals appear to be common in the 

 Congo, where they have undergone a great amount of differentiation 

 but appear to be relatively rare in the Sudan. 



Unfortunately, all of the skulls in this small series are so badly 

 broken that only on the type could cranial measurements be taken. 



Heliosciurus gambianus bongensis (Heuglin) 



Sciurus bongensis Heuglin, Reise in Nordost-Afrika, vol. 2, p. 59, 1877. (Bahr-el- 

 Ghazal.) 



Specimens Examined: Six, all in BM, from: Bahr-el-Ghazal, 2; 

 Tobbo, 2; Chak Chak, 1; Khor Gitti, 1. 



Measurements: No external measurements are available for adult 

 animals, but the skull of an adult male from Khor Gitti measures as 

 follows: Greatest length 42.3; condyloincisive length 37.4; gi-eatest 

 width across zygomatic arches 24.9 ; length of nasals 11.9; crown length 

 of upper toothrow 8.2. 



Remarks: This subspecies is not too uniform in color from the 

 localities examined but it is appreciably darker than canaster from the 

 Jebel Marra. The underparts are faintly buffy as opposed to white 

 in canaster. The perineal region is bright rufous in bongensis. 



The skulls of this subspecies may be distinguished from those of 

 canaster by the shorter nasals, smaller bullae, and a smaller but more 

 rounded braincase. 



Heliosciurus gambianus canaster Thomas and Hinton 



Figure 4,b 



Heliosciuuis bongensis canaster Thomas and Hinton, Proc. Zool. Soc. London, 

 p. 256, July 6, 1923. (Foothills of the Jebel Marra.) 



Specimens Examined: Four, all in BM, from the type locality. 



Measurements: The type, an adult male, and two adult females 

 from the type locaUty, respectively measure as follows: Length of 

 head and body 178, 173, 171; length of tail 217, 187, 208; length of 

 hind foot 44, 42, 45; length of ear 15.5, 19, 15; greatest length of 

 skull 43.7, 43.7, 43.6; condyloincisive length 38.2, 38.2, 37.9; greatest 

 width across zygomatic arches 25.5, 26.4, 25.4; length of nasals 13.6, 

 13.7, 13.0; crown length of upper toothrow 8.6, 8.1, 8.4. 



Remarks: Insofar as color is concerned, H. g. canaster and //. g. 

 Uteris approach one another quite closely. In the former, though, 

 the color is just a bit less intense and the rufescent perineal region, 

 absent entirely in the latter, is present to a slight degree. 



