46 



ATKINSON. 



gradually displaced Mus rattus. It is a burrowing animal and frequents 

 drains and cellars. There is a little to choose in color between this 

 and the black variety. The brown rat is grayer and of a lighter shade, 

 and this color is more noticeable when a number of the two species are 

 examined together. The tail is shorter than the head and body together, 

 and ends in a blunt point. The ears are short. 



(c) Mus musculus Linn., the common mouse. This resembles M. 

 rattus rather than M. decumanus. 



(d) Sorex giganteus Is. Geoffr., the musk rat or musk shrew. This 

 is neither a rat proper nor a rodent, but belongs to the insectivora. Its 

 outline closely resembles that of a rat, but it is appreciably smaller than 

 M. rattus. It is distinguished by its overpowering, musky odor. 



There are also hybrid varieties, presenting the long ears of Mus rattus 

 and the short, coarse tail of decumanus, the typical characteristics of 

 the different species being only attained by the adult male. 



The following roughly gives the percentages of the different species 

 of rats met with in Hongkong: 



Per cent. 



Black rats, Muss rattus 12 



Brown rats, Mus decumanus 18 



Mice, Mus musculus 48 



Sorex giganteus 2 



Hybrid rats, size of M. rattus 5 



Undetermined rats 15 



Table I. — Showing the number of cases of plague known to have occurred in the colony 

 each month from 1895 to 1904. 



Month. 



1895. 



1896. 



1897. 



1898. 



1899. 



1900. 



1901. 



1902. 



1903. 



1904. 







49 

 125 





9 

 67 



1 



8 



7 



1 



4 













168 





137 



25 





54 





115 



4 





3 



316 





468 



101 



94 



160 



27 



979 



40 





2 



344 



3 



534 



421 



326 



701 



157 



515 



135 



June 



13 



113 



1 



92 



514 



325 



551 



194 



343 



194 



July 





52 



11 



7 



263 



209 



109 



131 



85 



96 



August 



4 



25 



1 



2 



86 



SO 



27 



50 



32 



19 



September 



3 



9 



1 



1 



57 



16 



24 



2 



9 



9 







2 

 1 



2 



2 



4 



1 



12 

 2 



1 

 1 



2 

 1 



5 



4 



Nil. 



November 



5 



December 

 Total 



12 





2 



1 



11 



2 



2 



4 



2 



5. 



44 



1,204 



21 



1,320 



1,486 



.1,087 



1,651 



572 



1,415 



510 



1 



