226 



THE ARACHNOIDS. 



female gorges herself with blood; afterward dropping off the animal 

 and laying eggs. With some ticks fewer hosts suffice. 



Classification of Ixodidae. 



Subfamily Argosinae. Head concealed by bcdy when viewed 

 dorsally. No scutum. Stigmal plates between third and fourth legs. 

 Adults have no suckers beneath claws. 



FIG. 70. Ticks, i, Dorsal aspect of female Ixodinae; 2, ventral aspect of same; 

 3, dorsal aspect of male Ixodinas showing larger scutum or shield; 4, ventral aspect 

 of same; 5 and 6, ventral and dorsal surface of Ornithodoros moubata (Argasinae); 

 7, mouth parts of tick; 8, Stigmal plate of tick. 



Genus Argas. Body narrow in front. Margins thin and acute. 

 No eyes. The A. persicus (Miana bug) of Persia has been supposed to 

 be concerned in the transmission of a serious disease. 



Genus Ornithodoros. Margins of bcdy rounded. Skin has many 

 irregular tubercles. O. savignyi has 2 pairs of eyes near base of 



