BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 27. AFD. IV. N:0 4. 19 



Here, if we choose the per cent number for these ave- 

 ragespecimens which are most like each-other in the size of 

 the body, we find, for instance 



A rather wide gap here divides the Fa/^Zw-group from the 

 reticulatus-gronT^, bnt only in the averages. The forma gra- 

 cilis is well divided from the pallidus-iovvn, but not from the 

 typical Vahlii, which as to the grade of development holds 

 a lower position than palliclus. The frigidus-iovTa has almost 

 the same maxima and minima as seminudus, and the resp. 

 maxima of these two forms exceed the minima of the typical 

 reticulatus. Thus here are no constant characters to be found, 

 but the evolution goes on with the form-series, and it is 



