N. CUNLIFFE 
373 
Fig. 1. Rhipicephalus sanguineus, unfed larva: dorsal and ventral aspects, 
and tarsus 3. No. 1932 (8). N. C. del. 
Unfed larvae, the progeny of a single female, were placed on a rabbit 1 , 8. iv. 13. 
A. 
B. 
288 partly gorged larvae were picked off 
between the 3rd and loth days ; nymphs 
emerged on 19. iv. 13, metamorphosis 
lasting 8 days 2 , and were placed on the 
rabbit on 24. v. 13. 
C. 
D. 
26 nymphs, partly 
gorged, were picked 
off between the 4th 
& 10th days; adults 
emerged on 9. vi. 13, 
metamorphosis last¬ 
ing 12 days. 
Set I. 
527 fully gorged larvae dropped off the 
rabbit between the 2nd and 28th 
days; nymphs emerged on 18. iv. 13, 
metamorphosis lasting 8 days, and were 
placed on the rabbit on 13. vx. 13. 
E. ,-1-, F. 
11 nymphs, fully 
gorged, dropped off 
between the 5th & 
15th days; adults 
emerged onll.vi.13, 
metamorphosis last¬ 
ing 13 days. 
Set II. 
13 nymphs, partly 
gorged, were picked 
off between the 5th 
& 12th days ; adults 
emerged on l.vn.13, 
metamorphosis last¬ 
ing 13 days. 
Set III. 
11 nymphs, fully 
gorged, dropped off 
between the 5th & 
8th days; adults 
emerged on 2. vxi. 13, 
metamorphosis last¬ 
ing 14 days. 
Set IV. 
Variation in Nymphs. Fig. 2. 
The measurements of the nymphal scuta were taken and are 
recorded below. In each case the extreme examples were picked 
out and examined. 
The length of the scutum of the smallest nymph in Set A is only 
83 °/<, of that of the smallest in Set B. The scutum of the largest 
nymph in Set A is approximately as long as that of the smallest nymph 
in Set B. At the same time, it should be noted that the normal 
1 The rabbit was kept in a cage in the laboratory of which the average temperature 
was about 16° C., and the ticks, during metamorphosis, in an incubator maintained at 
30° C. 
2 In each case, only the minimum period required for metamorphosis is mentioned. 
