36 



PROCEEDINGS OF THE ACADEMY OF 



[Jan., 



Of the general Michigan series, 42 are from the Upper Peninsula 

 and 183 are from the Lower. As shown by figs. 5 and 12, the curve 

 of widths in both series is very similar. This being so, if the Upper 

 Peninsular examples from the general series are added to the Isle 

 Royale series, we shall have a fair basis for comparison of the species 

 as between these two portions of the State. There are then 166 

 Upper Peninsular specimens and 183 from the Lower Peninsula. 



Fig. 14 — Heights — a to b, 183 Lower Peninsula; c to d, 166 Upper Peninsula. 



The Lower Peninsular series varies in height from 12 to 24.25 mm. 

 with an average of 18.10. The Upper Peninsular series ranges from- 

 14 to 21.50 mm., with an average of 17.02. 



The Lower Peninsular series not only has a much wider range of 

 variation, but is more variable within that range. 



Both series are alike in having a conspicuous mode at 17 mm. 

 But the conspicuous modes at 16 and 21.75 mm. in the Lower Penin- 

 sular series are practically lacking in the Upper Peninsular series. In 

 other respects the two curves are very similar. 



Fig. 15— Widths — a to b, 1S3 Lower Peninsula; c to d, 166 Upper Peni nsu 



In width the two series show the same general similarity, exhibiting 

 great variability with conspicuous modes at nearly the same points, 

 the Lower Peninsular series differing mainly in the prominent modes 

 at 29 and 30.5 mm. and in the greater range of variation. 



