172 DISEASES OF POULTRY. 



considerable number of both wild and tame pigeons 

 and rarely found the connective tissue free from this 

 parasite. He found it chiefly in the subcutaneous 

 connective tissue around the large veins of the neck, 

 and on the surface of the pericardium. No disturb- 

 ance of the health has been observed to result from 

 the presence of this parasite. -- 



Passing now to the fourth group of epizoa, those 

 which live upon, or within, or among the feathers, but 

 do not bite or puncture the skin, we find included an 

 extensive list of lice and mites. The lice of birds be- 

 long exclusively to the pennivorous varieties, that is, 

 they subsist upon the feathers, and perhaps also upon 

 the epidermic scales, but they do not suck blood. It 

 is a curious fact that the blood -sucking lice all live 

 upon the mammalia. The lice of birds vary greatly 

 in size, the largest varieties being one -sixth of an 

 inch long, and the smallest not more than one -thir- 

 tieth of an inch in length. 



Young chickens hatched under hens nearly always 

 have lice upon them. These are found upon the head 

 and under the throat, where they have fixed them- 

 selves to the feathers near to the skin, and may be 

 mistaken for pin -feathers upon superficial examina- 

 tion. When badly infested, the parasites may also be 

 seen under the wings and about the vent. A number 

 of different kinds of lice may be found at one time on 

 the same bird, and, it may also be added, each species 

 of birds has its own species of lice. The lice are 

 more or less injurious to the plumage of infested 

 birds, they cause itching by roaming over the skin, 

 and they prevent the birds from obtaining their 

 proper rest. 



The mites of the fourth group cause little or no in- 



