22 Bulletin American Museum oj Natural History [Vol. XLVII 



Represented by 105 specimens, of which 99 are skins with skulls; 6 

 fcetal and young specimens in alcohol, and several skeletons, collected as 

 follows : 



Medje, 20: May and August-October 1910; November 8, 1913; 

 March 17-20, 1914. 



Nala, 1 (alcoholic) : July 1913. 



Akenge, 5: September 29-October 19, 1913. 



Niapu, 79: November 8-December 26, 1913. 



The 99 specimens represented by skins and skulls consist of 56 males 

 and 43 females, of which 76 are adult and 23 more or less immature. The 

 latter range in age from one specimen in which the milk teeth had not 

 pierced the gum to those with the deciduous dentition fully developed (a 

 series of 11 specimens), and the other 12 specimens fully illustrate the 

 transition from the deciduous to the permanent teeth. It has hence 

 seemed desirable to utilize this abundant material for the illustration of 

 the tooth development of this interesting genus of insectivores. (Text 

 figure 1, stages 1 to 8.) 



The large series of adults from Niapu (43 males, 25 females) affords 

 the basis for a study of sex, age, and individual variation. In the fol- 

 lowing tables (Tables 1-3, pp. 23-25) the external measurements, carefully 

 taken by the collectors before skinning, have been combined with three 

 measurements of the skull (total length, condyloincisive length, and 

 zygomatic breadth). Table 1 gives the measurements of the males, 

 Table 2, of the females, and Table 3 is a summary of Tables 1 and 2. 

 In these tables the specimens are arranged in four categories, according 

 to age as indicated by the amount of wear shown by the teeth, the 

 purpose being to determine the influence of age upon the general size of 

 the animal after the permanent dentition has been fully acquired. Table 

 4 is designed to show the correlation of growth with the tooth develop- 

 ment. Of the 18 specimens included in this table, 5 are from Medje and 

 13 from Niapu, those from Medje being indicated by an asterisk. 



Sexual Variation 

 There is no appreciable difference in size or coloration due to sex. 

 The average total length (tip of nose to end of tail) in 43 adult males is 

 515 mm., in 25 adult females, 516 mm. The average total length of the 

 skull for the same specimens is, males 68.1, females 68.5; condyloincisive 

 length, males 62.3, females 63.5; zygomatic breadth, males 36.3, females 

 36.2. 



