ot 
Sy 
PARASITOLOGY. 
Fig. 18—Male PsoRorpTES COMMUNIS, variety Ovis. Photomicrograph 
1x% inch. 
a, Head parts. b, Legs. 
c, Body. (Thorax and abdomen are not distinctly marked macroscop- 
ically.) 
asites, cause the hair to become matted and present 
a stairy appearance. Later the hair falls out and 
reveals scabby hairless patches. The mode of spread 
of the contagion, and the treatment, are the same as 
in scabies produced by other parasites. If the dis- 
ease is not treated the animal becomes thin in flesh, 
anemic, and finally dies. 
PsorRopTeEs CoMMuNIS, variety Bovis (Bovis—ox). 
History.—Widely distributed in the United States; 
found in the middle West and South. 
Animal Infested.—This is the common scab para- 
site of the ox. 
Condition Produced.—The back, loins and croup 
are the first parts to become infested. On account 
of the difficulty in scratching these parts the scabs 
pile up, often an inch in thickness. The animal rubs 
and licks himself as a result of the pruritus, gradu- 
