191 O.J VARIETIES OK MUS RATTUS IN EUYPT. (if).'} 



Mus rattus in the Indian Reyioii. 



In the Indian Region in particular this species has been 

 burdened with a tremendous number of specific names, given to 

 any variety which did not appear to fit in with the existin" 

 descriptions ; and with a view of partially clearing up chis tangle of 

 names, I went into the matter at some length a few years back*. 

 Briefly summed up my conclusions were as follows : — 

 If the large towns and seaports, where the rat pf)pulation is 

 apparently as cosmopolitan as the human, are put out of con- 

 sideration it appears : — 



(i.) That in most locnlities three fairly distinct forms are 

 found ; 



(ii.) That in any particular locality individuals belonging to the 

 same form do not show much variation and intermediates 

 between the forms are comjmratively scarce ; 



(iii.) In most localities the same three forms are easily recog- 

 nisable though differing slightly from their corresijonding 

 varieties in other places, 



I, therefore, divided the species into three subgroups, re- 

 presenting the three forms, and distinguished them as follows : — 

 (i.) Jalorensis\ subgroup. 



Hairs of underparts white to their bases. Hind foot 30 mm . 

 (ii.) Rufescens subgi-oup. 



Hairs of underparts white with slate-coloured bases. Hind 

 foot 33 mm. 

 (iii.) Griseiventer subgroup. 



Hairs of undeiparts entirely slate-coloured or tipped with 

 fulvous. Hind foot 35 mm. 



In addition to the characters given above, the subgroups 

 appeared, from collectors' notes, to have slightly difterent habits, 

 the last-named being found chiefly in houses, Jalorensis in the 

 hilly districts, and Rufescens in the date-palms. 



On this plan, it became comparatively easy by careful I'eference 

 to original descriptions and specimens to refer almost, .-dl the 

 varieties which had been described, to one or other of the sub- 

 groups, and then, by noting the type locality of each variety, the 

 mass of names became reduced to a manageable and fairly logical 

 order. Where two desciiptions had been applied to rats fi'om 

 the same locality, it was in most cases at once obvious from those 

 descriptions that they were not synonyms but referred to in- 

 dividuals of difterent subgroups. 



Without more material I did not feel justified in making 

 further comment, but left the work as a foundation to be im- 

 proved and elaborated should a future opportunity arise. 



In 1907, in the Mem, Ind. Mus. i. no. 1, Dr. Hossack has 



* 'Fasciculi Malayenses,' i. Zool. pp. 28 et seqq. (1903). 



t I named the subgroups, not after the oldest species but after the one of whicli 

 the original description would leave least doubt as to the main characters of tlie 

 subgroup. 



Puoc. Zool. Soc— 1910, No. XLIII. 43 



