90 HENRY H. DONALDSON 
ty of the dried crania also act in a like manner on both the wild 
Norways and the domesticated Albinos. Calculation shows that 
the combined records for the European Albinos run somewhat 
above those for the Philadelphia Albinos. The figures are given 
in table 18. 
These results suggest for consideration several important ques- 
tions. As is seen in table 17, the mean cranial capacity of the 
Paris Norway series is 0.4 per cent less than that of the Phila- 
delphia series, while from table 16, we see that the Paris brain 
weight is about 2.5 per cent greater. It would appear from this 
that the Paris crania had shrunk about 3 per cent more than the 
Philadelphia crania. Again table 17 shows the capacity of the 
TABLE 18 
Mus norvegicus albinus. Showing the mean percentage deviation in cranial capacity 
of each of the three European albino series from the Philadelphia series taken as a 
standard 
SERIES MEAN PERCENTAGE 
DEVIATION 
Parisien oak Ne BO os en aGeam endo Pe a oes oh eee eeeee +4.9 
i Wravave (OLnT. 329 sey tee eR eee i ene Ni he Se ea —0.1 
\VAT( a anal tes Alpe eh SI hag RIE, Sor ers ar Pd ah —0.1 
IA VERA ONE EM cise. ioe Ohta Abie a ne ete Mi cs ores ee eae ce +1:6 
London crania to be about 2.5 per cent less than that of the Phil- 
adelphia crania while the brain weights are nearly identical; 
once more a greater relative shrinkage in the London series. The 
same thing has probably happened in the case of the Vienna 
series, but for this series the brain weight determinations are 
lacking. 
The albino records must also represent crania which have suf- 
fered more or less shrinkage characteristic for the series to which 
they belong, but as table 18 shows, two of the series run close to 
the Philadelphia standard, though slightly below it, while one, 
the Paris series, is clearly above it. As the preparatory treatment 
of all the skulls was the same, these variations in the amount of 
shrinkage must find their explanations in variations in the com- 
as represented by the amount of 
position of the skull bones 
