SYMPLECTOPTES MITES. 57 



in male and slightly larger in the female (fig. 18). 

 These minute mites are special to the Gallinaeeae. 



Fig-. 13. 



Symplectoptes cyst icola . 



They live in the connective tissue of fowls &c, but 

 they apparently never affect the health of the host. 

 They may give rise to the formation of tubercles, 

 produced by the irritation they set up. 



Heller, of Kiel, has found 70 per cent, of the fowls 

 affected by this tubercle, which appears in the peri- 

 toneum of the abdomen and viscera generally. Thev 



O ml «/ 



are particularly prevalent in old and diseased birds. 



Feather Mites. 



Another group of Acari known as Analgesince, or 



SarcoptidcB plumicoles, inhabit the feathers of birds : 



each bird nearly has its own distinct species of this 



minute group of mites ; some birds have more than 



