1922] Allen, Congo Collection of Insectivora 29 



Individual Variation 



Size. — As already noted incidentally above, the variation in total 

 length (tip of nose to end of tail) in the series of 25 young males with un- 

 worn teeth from Niapu covers the entire range of variation in the whole 

 series of the 68 adults from Niapu, all of which were taken within a period 

 of about six weeks in November and December of the same year, and all 

 within a radius of about six miles in strictly uniform environment. 

 Leaving out of consideration a single specimen (No. 49474, cf), obviously 

 a dwarf, the average total length is 510 mm., the two extremes being 465 

 and 556, a difference of 91 mm., 17 per cent of the mean. Even this is 

 exceeded in the old-age series of 7 males, where the range is 19.6 per 

 cent. This illustration applies equally to length of tail, where the range 

 of variation is 18.7 per cent of the mean, but not to hind foot and ear, 

 where the range is respectively 10 and 2 per cent. It is also much less in 

 the skull, in which the mean condyloincisive length in the 25 young 

 adults in question is 62.1 mm., and the extremes 60.7 and 64.1, and the 

 difference 3.4 mm., or only about one-half of 1 per cent. This, however, 

 is nearly equal to the variation due to age, where the average condylo- 

 incisive length in the old-age series of 11 specimens is 62.9 mm. (minimum 

 60, maximum 65 mm.). The variation in zygomatic breadth parallels 

 that of the skull length. 



Coloration. — Rhynchocyon s. claudi may be said to have, in a general 

 way, a light phase and a dark phase of coloration, but a large proportion 

 of the specimens in the present large series are in such varying degrees 

 intermediate that no line of demarcation can be even approximately 

 assigned. As the extremes of light and dark specimens belong to the 

 same sex and prove to have been taken on the same day at the same place, 

 it must be assumed that this wide range of color variation is purely in- 

 dividual. Yet, should single specimens of the extremes of the light and 

 dark types of coloration be received by a systematist from even the same 

 locality, he might be pardoned for considering them as nameable forms. 

 Some of the East African forms of Rhynchocyon have been found to be 

 notably prone to melanism, but among the hundred examples of the 

 claudi type collected by the American Museum Congo Expedition not 

 one shows such tendency, notwithstanding the large amount of color 

 variation they present. 



The light or reddish phase (Plate I, upper figure) may be indi- 

 cated as follows, beginning with the ventral area: 



Chin, throat, fore neck and pectoral region entirely and nearly uniform buff, 

 varying from pale buff to ochraceous buff (in different specimens), abruptly con- 



