50 



Genus Ornithodoros 



otherwise they conform to the adult in all essential characters. Nymphs 

 of intermediate sizes may be encountered down to the smallest or first 

 stage nymph after its ecdysis from the larval skin and the egg-shell. 

 In moulting (see Fig. 68) the skin of the adult or nymph splits along 

 a definite line on each side running from the front margin backward 

 above the spiracles, the tick emerging anteriorly, but the whole dorsal 

 cuticle may come off like a cap or adhere for some days to the tick 

 which has issued. Nymphs of the third stage attain 5 x 25 mm., 

 whereas unfed nymphs of the second stage average 14 x 1*2 mm. 



Fig. 70. 



Fig. 72. 



Fig. 71. 



Fig. 73. 



Figs. 70, 71. 0. savignyi. Distal ends of legs of adult of large size, (70) leg I and 



(71) leg IV. 



Figs. 72, 73. 0. moubata. Distal ends of legs of adult of large size (11 mm. I.), 



(72) leg I and (73) leg IV with tarsus 1-8 mm. I. 



(Donitz, 1906, pi., figs. 1, 3, 4, 6.) 



The Nymph (1st stage, Figs. 74 and 75), immediately after it has 

 emerged from the larval skin and the egg-shell, measures on an average 

 1 x "87 mm. After some time it becomes somewhat flattened and 

 longer, its contour being sub-circular and the colour ochreus. The 

 minute spiracle is situate as in adults, between legs III and IV. The 

 mammillations covering the dorsum extend but partially over the 

 postero-ventral border, the capitulum is well developed, the hypostome 



