50 Bulletin American Museum of Natural History [Vol. XL VII 



which deepens on the lower hind limbs and anal region to a much darker 

 tone, and is more or less strongly diffused over the basal portion of the 

 underside of the tail. The mid-abdominal region (axillae to loins) is a 

 grizzle of dull brown and pale buffy, with a tendency to a lighter median 

 line. The upper surface of the fore and hind feet is mixed dark rufous 

 and black, the black basal portion of the hairs showing more or less at the 

 surface. 



Individual color variation in adults is due primarily to the amount of 

 rufous suffusion present, varying from a strong rufous tone throughout 

 the pelage to its almost entire absence. Specimens of either of these 

 types, however, are exceptional. The specimen selected as type of 

 medjianus represents the average condition. The extreme rufous ex- 

 amples strongly approach rubricatus and indicate intergradation between 

 the two forms. The specimens recorded by Thomas from Medje and 

 Poko as referable to H . r. pasha (loc. cit.) should doubtless be referred to 

 medjianus, since these localities are in the type region of the latter. 



Heliosciurus rufobrachium rubricatus, new subspecies 



Type, No. 50748, cf adult, near the Lubila River, an affluent of the Tshopo River, 

 about 50 miles southwest of Avakubi (south of the Ituri River), Belgian Congo, 

 September 20, 1909; Herbert Lang and James P. Chapin, Orig. No. 123. 



Similar to H. r. medjianus in size and color of upperparts; underparts more 

 strongly suffused with rufous; inside of fore and hind limbs and anal region intense 

 dark rufous; upper surface of feet, wrists and ankles, and median basal underside 

 of tail chestnut-rufous. 



Collectors' measurements of type: Total length, 552 mm.; head and body, 255; 

 tail vertebrae, 297; hind foot, 61; ear, 19. 



Skull (type): Greatest length ( =occipito-nasal), 55.4; condyloincisive length, 

 51.2; least interorbital breadth, 16.7; tip to tip of postorbital processes, 25.6; 

 postorbital breadth, 14.4; breadth of brain-case, 23.1; zygomatic breadth, 31.5; 

 length of nasals, 17.6; breadth of nasals anteriorly, 8.3, do. at posterior border, 6.6; 

 length of maxillary toothrow, 10.9. 



Represented by 9 specimens, as follows: 



Avakubi, 7(3^,3 9 , all adult, 1 in alcohol), October 1, 13, December 8, 1909, 

 January 12, 24, June 22, and August 26, 1914. 



Bafwasende (35 miles south of Avakubi), 1 ( cT adult), September 23, 1909. 



Lubila, 1 (d 1 adult), September 20, 1909. 



Collectors' measurements of 6 specimens (3 cT, 3 9) from Avakubi: Total 

 length, 501 (482-525); head and body, 234 (226-253); tail vertebrae, 262 (251-279); 

 hind foot, 59.3 (54-63); ear, 18.3 (17-20). 



Skull (4 of same specimens — 2 too much broken for measurement) : Greatest 

 length, 53.4 (52.4-54.8); zygomatic breadth, 31.9 (29.7-33.4). 



The relation of the present form to medjianus has been indicated in 

 the detailed comparison already given (pp. 45 to 47) of the three forms 



