Manchester Memoirs, Vol. liv. (1910), /V(^ 10- 7 



autumnal mortality, and since then I have devoted con- 

 siderable time to accumulating evidence for or against 

 the theory which presented itself. 



The facts which I noticed were these. 



1. During and after December all specimens of both the 

 Common and the Lesser Shrew were immature ; and that 

 from this time till early spring it was impossible to deter- 

 mine the sex of either species without dissection. 



2. That during the same period all the females of 

 both species were without exception sexually immature — 

 the first exception not occurring till the middle of April. 



As is the case with the Mole, immature female shrews 

 closely resemble the males in outward formation.) 



3. That the genital organs of both sexes commence 

 to enlarge in February, and attain a remarkably large 

 size in May and June. In the case of the male the 

 development is relatively greater than even that of the Mole. 



4. That the tails and feet of winter specimens were 

 always in good condition, being thickly covered with hair, 

 whereas the tails and feet of both species are often 

 denuded of hair during the breeding season — almost 

 invariably so in the case of the Common Shrew — appar- 

 ently by the continual biting during the fights between 

 the males and, perhaps, the capture of the females by the 

 males. Possibly a summer moult may account for some 

 of the loss of hair. 



Now, what particularly struck me as curious was that 

 during and after December females that had already bred 

 should never be trapped, and that not a single adult male 

 should be recorded ; though I was prepared to find the 

 male organs atrophied, as is the case of the Mole after 

 the breeding season. I was at first disposed to regard 

 the hairiness of the tails as due to the acquisition of a 

 winter pelage, but considering the other evidence I am of 



