Skulls of 892 house mice of five species (Mus Linnaeus, 1758), collect
ed from 136 localities across Europe and Morocco, were studied. The an
alysis revealed that variations in size affected most of the character
s considered, indicating a need to size-adjust the data. M. domesticus
was morphologically the most variable of all the European mice yet th
is variability was not consistent with the distribution of subspecies
domesticus and brevirostris. The population from Albania was distinct
within the M. domesticus samples, resembling M. musculus in overall si
ze. In M. musculus, a W-E gradient of size was found in some variables
, especially in females, and a sex dimorphism appeared also in populat
ions from western parts of its range. Among 619 mice from 66 samples a
cross the Czech and Slovak Republics and western Ukraine, but not from
populations from western Bohemia, only M. musculus was substantiated.
In spite of the fact that M. spicilegus and M. macedonicus are geneti
cally and morpho logically very close, as many as 9 variables (both un
transformed and size-adjusted) proved to be different between the two
species while M. spretus was found to be morphologically intermediate.
The NW distribution limit of M. spicilegus is discussed.