140 
THE SHEEP-TICK. 
nal bristle, and situated in a depression near the mouth. 
This is a tubular proboscis, protected on the outside by two 
flat and elongated bristly pieces, the labrum. The organs 

Fig. 121.—Iiead ot sheep-tick. Original. Below uterus-like en- 
largement of oviduct. 
Greatly enlarged. After Leuckart. 
used in piercing the skin and in drawing blood are three long 
and slender bristles of equal length but unequal size, which 
are withdrawn when notin use. A glance at the illustration 

Fig. 122.—Young larva and 
puparium, with  breathing- 
pores, of sheep-tick. Greatly 
enlarged. Original. 
of ahead of thesheep-tick, (fig. 121), 
will explain this peculiar structure 
better than words. The abdomen 
is flat and bag-like. The whole in- 
sect is densely clothed with hair 
and bristles; the sexes resemble each 
other, the male being simply smaller. 
The life-histories of these para- 
sites are very abnormal, as they 
bring forth full-grown larve, which 
soon change to pupz without first 
taking food outside of the mother. 
Theinsect, instead of depositing an egg upon suitable food, as 
nearly all other insects are in the habit of doing, retains the 
same insidean uterus-like enlargement of the oviduct,(shown 
below head in fig. 121), where it is hatched. Here it is 
