GAMASIDS, 



169 



CASE the same genus of the same place of abode in two animals living 

 under such different conditions, a selection apparently followed or 

 attended by a certain similarity of appearance, due no doubt to the 

 equally restricted and confined limits of their place of abode. We 

 can imagine the Gamasus of the animal that became a seal, being 

 driven to take shelter in its nostrils to escape from being drowned 

 by the washing of the seas, to which it would be exposed if it 

 stuck to any unsheltered part of the body ; and the Dermanyssus 

 of the nostrils of the goat-sucker may have taken refuge there as 

 its only place of secure retreat from the danger of being scratched 

 off by the pectinated claw of its host. 



Sub-family Dermanyssid^e. 



Genus Dermanyssus. {Duges.) 

 Soft-skinned ; parasitic only on warm-blooded animals. 



No. 16. Dermanyssus nitzschii [Giebely in Zeit. ges. Naturw. iv. 29). — 16. En- 

 larged figure of ditto, copied from Giebel's figure. 



This is the species from the nostrils 

 of the goat-sucker, of which we have 

 above spoken. It feeds on the blood of 

 its victim; it is as big as a head-louse, 

 and as many as twelve to fifteen were 

 found together in the nostril of the same 

 bird. 



Nos. Dermanyssus avium {Dug.)—Vt. Enlarged 



19*, 20' figure of ditto, empty ; 18. Specimens thereof; 



21^ 19. Vignette of chickens (realistic chick) ; 20. 



Enlarged figure of ditto fed ; Si. Specimens 



thereof. 



Dermanyssus nitzschiJ. 



About the size of a head-louse. 



Copied from Giebel. 



The so-called "tick" that infests domestic poultry, canaries, and 

 other cage birds. It lives especially in f<5wl houses, and on their 



