xii EXPLANATION OF THE PLATES. 



Fig. 16. Still more mature, eight-legged example. The bases supporting the feet and 

 the hook in the centre of the free ends of the feet. The two side-hooks 

 of Simon are not true bristles or hooks, but the projecting points of the half 

 moon-shaped free ends of the feet, as is still more clearly represented in 

 fig. 16' a. 



'PLATE ix. 



Figs. 1 7. Itch mites, after Gudden. 

 Fig. 1. Female viewed from the back. 

 ,, 2. abdomen. 



,, 3. Male viewed from the abdomen. 



4. Group of mites, with eggs in various stages of development. 

 ,, 5. Cast-off skin, remaining behind in a passage after the first moulting. 

 6. Six-legged mite, as, in order to moult, it conceals itself in its gallery, and draws 



near to it masses of particles and repairs itself in quiet. 

 7. Eight-legged mite, which has just moulted in the gallery. 

 8. Lepius autumnalis, after a drawing kindly given to me by Prof. Leuckart. 

 9. Male louse from the head, w r ith the system of tracheae and the respiratory 



stigmata. 



Fig. 9 a. Termination of the head and working apparatus. 

 ,, 9 b. An isolated and magnified antenna. 

 10. Female body louse. 

 ,, 11. Its masticatory apparatus. 



12. Egg of a louse, found on the hair of a Peruvian mummy. The cover has unfor- 

 tunately been neglected to be drawn. The description of the cover of the egg 

 of this louse is found in the text in the place relating to it. 



13. Female louse, with the system of trachea, and the two muscles moving the 

 hooks of the second and third pairs of feet at a, which give the last joints 

 the appearance of a bell. 

 14. Head of the flea. 



15. His double, at first spirally wound-up penis. 

 Figs. 1618. Larvae of the Gad-Fly of Cervus Capreolus. 

 Fig. 16. The same larva seen from the abdominal side, and magnified, a, kind of 



depression, in which the anal aperture opens. 



b. The four bundles of muscles which shine through the body of the larva, and 

 ce, two small brown valves. 



17. The same, seen from behind. On the head is seen two small, scarcely per- 

 ceptible dark brown hooks, also the fine prickles on the segments, and a dark 

 spot on the rounded-off back part of the tail. 

 18. A piece of a trachea with the little valve still fastened on it. 



