\j. E. Robinson 
15 
0-85 approximately. In the case of Lot No. C. 309, comprising 64 males, 
collected at Gonubie Park in 1908 by Mr W. F. Cooper, it is seen (Fig. 2) 
that the length of the scutum ranges between 5-4 mm. and 3-5 mm., 
the maximum and minimum breadths are 4-7 mm. and 3-2 mm. respec¬ 
tively, while the mean ratio has risen to 0'87. For purposes 
of comparison, these figures are set out in tabular form below: 
Measurement 
Lot No. C. 263 
(collected in 1905) 
Lot No. C; 309 
(collected in 1908) 
Maximum length 
5-7 mm. 
5-4 mm. 
Minimum ,, 
4-2 
3-5 
Mean ,, 
4-97 
4-56 
Maximum breadth 
4-9 
4-7 
Minimum „ 
3-5 
3-2 
Mean ,, 
4-22 
40 
. breadth 
Maximum , , ratio 
length 
0-94 
1-00 
Minimum „ ., 
0-78 
0-77 
Mean „ ,, 
0-85 
0-87 
A comparison of the two diagrams shows a striking difference in 
the general disposition of the square dots representing the individual 
ticks; in Fig. 1 the dots are collected in an elongate but moderately 
compact group, while in Fig. 2 they are widely scattered; a fact which 
is, of course, explained by the greater variability in size of the ticks 
which had lived under the adverse conditions brought about by the 
measures taken for tick eradication. 
Fig. 3. Amhlyomma hebraeum cJ. The scuta of the largest and smallest individuals of 
Lot No. C. 309. Magnified 10 diameters. 
