SCIENTIFIC RESULTS FROM THE MAMMAL SURVEY. 419 



genus Leggada, which was used for a number of yesrs as valid, 

 and then more recently (Miller, Mamm. W., Europe, p. 863, 1912) 

 united with Mies. 



I have therefore again examined all the pertinent African species 

 to see how far the natural grouping corresponds with that of the 

 Indian ones, and if so whether the grovips can be defined satis- 

 factorily. 



The geography of the case has first to be considered. For in the 

 East all the true native Indian forms come under B, those fallino- 

 under A being either the artificially transported and parasitic 

 muscul'us, or else Paleearctic in locality. Should we therefore find 

 that in the west those corresponding to A were again Paleearctic 

 and those to B Ethiopian, the case for separation would be 

 greatly strengthened. 



And this is exactly what we do find. The short-muzzled, muscu- 

 lus-liJie forms range over the whole of Europe, are found in North 

 Africa and in Egypt, along the Nile as far south as Khartoum, but 

 beyond that are not found in any part of Africa, the Ethiopian 

 forms being all of the B type. 



We thus find that the A group is by nature Palgearctic only, a more 

 or less artificial extension of it southwards to Khartoum in Africa 

 and over all India being effected by the parasitic habits of Mus 

 musculus itself, just in the regions of the ancient civilizations of 

 Egypt and India. And on the other hand the B group is Ethio- 

 pian and Oriental, not penetrating at all into the Palgearctic. 



This seems to indicate that the groups A and B, or to call them 

 now by their technical names, Mus and Leggada, are really distinct 

 natural groups which it would be both convenient and true to 

 nature to recognise as separate. 



The essential characteristic of 31us, as compared with Leggada 

 is the shortening of the muzzle, a shortening which is emphasised 

 by a somewhat more forward position of the anterior zygoma-root. 

 Looking at the skull from below the whole zygomatic plate is 

 pushed forward, so that its anterior edge comes opposite a point in 

 front of the middle of the palatal foramina while in Leggada it is 

 at or even behind the middle. The length of the nasals in Mus 

 is generally about equal to the distance from the external edge of 

 one tooth-row to the outer side of the zygoma of the opposite side, 

 or (perhaps a better comparison j to the distance between the lips 

 of the auditory meatus of the two sides. In Leggada the nasal 

 length generally decidedly surpasses these two distances. Not 

 only is the muzzle of Mits shorter, but it is a little broader, 

 so that the distance between the two anteorbital fossa? goes less 

 than three times in the nasal length, in Leggada more than three 

 times. 

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