164. RATS AND PLAGUE. 
Stegomyia mosquito of yellow fever so the rat-flea Pulex cheopis 
‘is the disseminator of plague which is spread so far as is known 
at present by its agency alone. ‘The simplest method of elim- 
imating danger from the flea is to destroy the rat on which 
it exists and of which it is carried about. 
Mus griserventer, a somewhat aberrant member of the rattus 
group approaching M. decwnanus in the harsh nature of its 
pelage and size of feet, is the commonest house-rat throughout 
the Malay Peninsula—in the southern half at any rate. It is 
found everywhere in the neighbourhood of man as is also Mus 
concolor, a diminutive form of Mus rattus with a very spiny 
coat. 
In external appearance Gunomys varius and Mus 
decumanus seem somewhat alike on superficial examination and 
both attain a head-and-body length of nine to ten inches, the 
latter sometimes reaching nearly a foot. There are however 
many points of difference. _ 2 
In Gunomys varius the pelage is thin and meagre in quanti- 
ty, especially on the abdomen, and cold in tone, the upper surface 
being a mixture of black and buff. Its tail is uniformly dark 
and clad with dark hairs and is somewhat short (about 80% 
~ or less of the length of head and body). Its feet have dark 
_ hairs on their. upper surfaces. : 
Mus decumanus is fairly thickly clad with fur of a warmer 
colour, that of the back being mingled sooty and ochraceous. 
Its tail is flesh-coloured on the basal half of the under 
surface and this area produces pale hairs which contrast 
with the brown hairs of the brown upper surface: it also nearly 
approaches (90 per cent) the length of the head and body. The 
feet are flesh coloured with white hairs onthe upper surface. 
The under surfaces of both animals are of a silvery or smoky 
pray... ge : : 
- A differentiating character for the genera of Mus and 
Nesokia (Gunomys) givenby Stanford and others is that the upper 
incisors of the latter are, on the outer surface, sculptured with 
faint longitudinal grooves while the front teeth of Mus are 
smooth. Dr. Hossack has, I think rightly, pointed out that this 
Jour, Straits Branch 
