1922] Allen, Congo Collection oj Insectivora 27 



Age Variation 



Coloration. — Coloration is only slightly affected by age. In 

 young specimens in the first pelage, the tones are practically the same as 

 in adults; the light and dark markings of the upperparts are not quite so 

 sharply defined, but the pattern is strictly the same. In very old speci- 

 mens the dorsal pelage has sometimes a more grayish cast than is usual 

 in younger animals,- due perhaps to less prompt renewal. As will be 

 shown later, the wide variation in color seen in a series of specimens has 

 no relation to sex or age. 



Size. — Tables 1-4 have been compiled with special reference to the 

 effect of age upon the general size of the animal and upon the size of the 

 skull, since species and subspecies are sometimes based on adolescent 

 specimens, and frequently on " young adults." Table 4 shows that in 6 

 specimens having only the full deciduous set of teeth the total length 

 (tip of nose to end of tail vertebras) ranges from about 440 to 460 mm. 

 as compared with the average adult length of about 515 mm., and a con- 

 dyloincisive length 1 of about 50 to 60 mm., as compared with about 63 mm. 

 in middle-aged specimens. During the period of the replacement of the 

 deciduous by the permanent teeth the size increases to about the mini- 

 mum for adults, the total length averaging about 500 mm. and the 

 condyloincisive length about 60 mm. 



The average total length of the animal in 38 specimens (24 males, 14 

 females) with unworn teeth is 514 mm. (males 509, females 524) ; aver- 

 age condyloincisive length of skull, 62.3 (males 62.1, females 62.8). 



In 8 specimens (6 males, 2 females) slightly more advanced in age 

 (the teeth appreciably worn) the average total length is 516 mm. (males 

 520, females 501); condyloincisive length of skull, 62.3 (males 62.5, 

 females 61.5). In this case the number of specimens is too small to be 

 satisfactory, especially in relation to sex difference in size. 



In 9 specimens (4 males, 5 females) still older (teeth much worn), the 

 average total length is 524.4 mm. (males 523, females 527) ; condyloin- 

 cisive length of skull, 63.27 (males 63.25, females 63.5). Again the 

 series is too small for satisfactory results, but is not wholly without 

 interest. 



The old-age (senile) series is represented by 11 specimens (7 males, 

 4 females). The average total length is 512 mm. (males 511, females 514) ; 

 condyloincisive length, 62.9 (males 62.6, females 63.5). 



J The condyloincisive length is a better standard than total length of skull, the cssificaticn cf the 

 nasal cartilage being a variable element, sometimes terminating at cr a little behind the tip of the 

 premaxillse but usually extending several millimeters beyond this point. Hence, total length srd oc- 

 cipitonasal length are undesirable measurements for skulls of Rhynchocyon. 



