THE TERRAPIN SCALE. 5 



This material was taken from vigorous trees. Twigs containing 

 about 200 specimens were cut to secure material for each measure- 

 ment. To overcome the natural variation in size the 50 largest speci- 

 mens were removed from the twigs and the largest of these taken 

 each time for measuring. These measurements show the following 

 maxima: 



Length, May 16, 1912 3.7 mm. 



Width, May 30, 1912 3.35 mm. 



Height, May 24, 1913 1.60 mm. 



Table I. — Measurements showing growth of 414 females of the terrapin scale during the 

 spring development, Mont Alto, Pa., 1912 and 1913. 



Date. 



Num- 

 ber of 

 speci- 

 mens. 



Length. 



Mini- 

 mum. 



Maxi- 

 mum. 



Aver- 

 age. 



Width. 



Mini- 

 mum. 



Maxi- 

 mum. 



Aver- 



Height. 



Mini- 

 mum. 



Maxi- 

 mum. 



Feb. 24, 1913 

 Mar. 28, 1913 

 Apr. 8, 1913. 

 Apr. 10, 1912 

 Apr. 11, 1912 

 Apr. 16, 1912 

 Apr. 17, 1913 

 Apr. 19, 1912 

 Apr. 22, 1912 

 Apr. 23, 1913 

 Apr. 26, 1912 

 Apr. 28, 1913. 

 Apr. 30, 1913 

 May 6, 1912.. 

 May 7, 1913. 

 May 10, 1913. 

 May 16, 1912. 

 May 16, 1913. 

 May 23, 1913. 

 May 24, 1913. 

 May 30, 1912. 

 May 31, 1913. 

 June 3, 1913- 

 June5, 1912. 

 June 7, 1913. 

 June 20, 1913 

 June 28, 1912 



Total. 



Mm. 



1.80 



1.726 



1.825 



1.81 



1.85 



1.6 



1.87 



2.05 



1.7 



2.24 



1.975 



2.613 



2.706 



2.5 



2.893 



2.8 



2.65 



2.94 



2.8 



2.8 



2.5 



2.983 



2.893 



3.05 



2.8 



2.52 



2.6 



Mm. 



2.375 



2.053 



2.31 



2.2 



1.9 



2.55 



2.53 



2.7 



2.3 



2.98 



2.925 



3.427 



3.042 



2.975 



3.22 



3.266 



3.7 



3.621 



3.38 



3.36 



3.525 



3.453 



3. 593 



3.5 



3.36 



3.173 



3.05 



Mm. 



2.076 



1.891 



2.114 



1.995 



1.88 



1.926 



2.195 



2.372 



2.057 



2.576 



2. 314 



2.866 



2.94 



2.666 



3.024 



3.021 



3.127 



3.204 



3.046 



3.170 



3.217 



3.177 



3.113 



3. 275 



3.102 



2.947 



2.887 



Mm. 

 1.8 



1.633 



1.87 



1.75 



1.8 



1.5 



1.842 



2.1 



1.6 



1.82 



1.725 



2.24 



2.473 



2.3 



2.501 



2.52 



2.65 



2.52 



2.61 



2.706 



2.7 



2.613 



2.613 



2.5 



2.66 



2.426 



2.7 



Mm. 



2.275 



2.146 



2.255 



2.2 



1.9 



2.35 



2.365 



2.375 



2.25 



2.813 



2.625 



3.033 



2.94 



2.675 



2.893 



2.893 



3.3 



3.173 



3.22 



3.266 



3.35 



2.986 



3.08 



3.1 



3.22 



2.986 



3.30 



Mm. 

 2.030 



1.758 



2.060 



1.905 



1.833 



1.828 



2.037 



2.302 



1.900 



2.298 



2.200 



2.566 



2.721 



2.458 



2.639 



2.674 



2.94 



2.951 



2.851 



2.950 



3.067 



2.844 



2.811 



2/8 



2.885 



2.717 



2.85 



Mm. 



0.725 

 .65 

 .73 

 .8 



.S65 

 .825 



,85 



.925 

 1.00 

 1.00 

 1.2 

 1.05 



1.225 



1.15 



1.225 



1.07 



1.20 



1.20 



1.325 



1.275 



1.22 



1.075 



Mm. 



1.10 

 .85 

 .975 



1.15 



1.1 



1.00 



1.225 



1.275 



1.3 



1.25 



1.50 



1.50 



1.19 



1.475 



1.60 



1.43 



1.49 



1.55 



1.375 



1.525 



1.525 



1.5 



Mm. 

 0.908 

 .741 



.854 



.953 

 .922 



.995 



1.118 

 1.165 

 1.437 

 1.343 

 1.317 



1.365 



1.333 



1.435 



1.352 



1.319 



1.392 



1.35 



1.383 



1.384 



1.282 



It is doubtful whether individuals ever are large enough to have 

 all the above measurements, since excessive size in one dimension is 

 accompanied by a smaller size in the other dimensions. 



The date of greatest average measurements of the same 414 speci- 

 mens are: 



Mm. 



May 30, 1912, length (7 specimens) 3.217 



May 30, 1912, width (7 specimens) 3.067 



May 6, 1912, height (6 specimens) 1.437 



It is evident from these data that the females reach their maximum 

 size between the middle of May and the end of the first week in June. 



