1922] Allen, Congo Sciuridae, Anomaluridae, Idiuridse 45 



Heliosciurus Trouessart 

 Heliosciurus (subgenus of Sciurus) Trouessart, 1880, Le Naturaliste, II, 

 October, p. 292. Genotype, by subsequent designation (Thomas, 1909), Sciurus 

 gambianus Ogilb} 7 . Trouessart originally designated Sciurus annulatus Desmarest as 

 the tj 7 pe, but as this species is not positively identifiable Thomas has, with good 

 reason, replaced it by Sciurus gambianus Ogilby. 



The Heliosciurus rufobrachium 1 group is represented in the Lang- 

 Chapin Collection by 57 specimens, collected in the region comprised 

 between Avakubi and Bafwasende, south of the Ituri-Aruwimi River, 

 northward to Niangara, on the Uele River, and eastward to Faradje. 

 Three geographical areas are thus included — (1) the region south of the 

 Ituri-Aruwimi covered with Rain Forest, (2) the forested area between 

 the Ituri-Aruwimi and Bomokandi-Uele rivers, and (3) the Uele bush- 

 veldt district to the north. The specimens from these districts, when 

 arranged serially, show well-marked differences in coloration in correla- 

 tion with the varying conditions of the districts, the extremes represented 

 — the Avakubi specimens on the one hand and the Niangara-Faradje 

 specimens on the other — being so widely different that, without the con- 

 necting series from intermediate points, they might readily be con- 

 sidered as possibly specifically separable, especially if represented by a 

 single specimen or even by a small series of specimens. The specimens 

 from the intermediate localities show, however, unmistakable inter- 

 gradation between the two extreme geographic phases. The differences 

 are primarily the amount and intensity of rufous on both fore and hind 

 limbs and the color of the whole ventral area, particularly of the throat 

 and inside of the limbs. Also the northern pale veldt form is distinctly 

 smaller than either of the two forest forms. The main feature of differ- 

 entiation is the steadily increasing erythrism of the ventral surface and 

 limbs from the northern veldt country to the heavy Rain Forest south of 

 the Ituri. 



In the coloration of the upper surface there is little to distinguish 

 the specimens from the three areas, although the Niangara and Faradje 

 specimens average somewhat paler than those from farther south. 



'Mr. Lang has called my attention to the fact that Sciurus rufobrachium Waterhouse has nearly 

 three months priority over .S. rufobrachiatus of the same author and it should therefore be accepted 

 in place of the latter. The species so long universally known as Sciurus rufobrachiatus was named 

 Sciurus rufobrachium by Waterhouse in an incidental reference to it in a footnote to a paper in the 

 'Annals and Magazine of Natural History' (X, p. 202) published in November 1842, but in his formal 

 description of the species (Proc. Zool. Soc. London for 1842, p. 128, published January 1843) he changed 

 the name to Sciurus rufobrachiatus, without explanation or reference to the earlier name for the same 

 species. Consequently the name Sciurus rufobrachium was used by just a few, Fitzinger (1867) being the 

 last. All succeeding authors have either overlooked or ignored the earlier name till it was brought to 

 light by Mr. Lang in the preparation of his paper on the bibliography and distribution of African 

 members of this group. 



It may be noted also that Waterhouse's Sciurus leucogenys has priority over his Sciurus erythro'genys, 

 the two cases being parallel and dating from the same footnote. 



