34 Arachnida and Myriopoda 



6 



i 



I 



8 



Eyes absent. Coxa of first leg never 



bifid. Trochanter of first leg with 



a distinct retrograde spur. Anal 



plates absent ... ... ... Haemaphysalis. 



Eyes present ... ... ... ... ... ... 7 



Anal plates present in male (some- 

 times fused to form a single plate) ... ... ... 8 



Anal plates absent ... ... ... ... ... ... 9 



Scutum of male, with distinct fes- 

 toons posteriorly. Stigmata 

 usually comma-shape ... ... Bhipicephalus. 



Festoons absent. Scutum of female 

 small. Anal groove obsolete. 

 Stigmata rounded or oval ... Margaropus. 



Base of capitulum hexagonal dor- 

 sally, the sides projecting in 

 angles. Scutum not ornamented Bhipicentor. 



Base of capitulum rectangular dor- 

 sally. Scutum usually ornamented 

 with designs ... ... ... Dcrmacentor. 



Tbe Ixodoidea are mostly Acari of large size, and are popularly 

 known as ticks. They are closely allied to the mites of the family 

 Parasitidae (Gamasidae). There are two principal divisions or 

 families of ticks, viz., the Argasidae and the Ixodidae. 



Family— ABGASIDAE. 



The ticks of the family Argasidae are not furnished with any 

 dorsal shield (scutum) ; while the capitulum (rostrum) is ventral 

 in position, and cannot be seen from above, being hidden by the 

 front end of the body. There is no marked difference between 

 the sexes, but the male is usually smaller than the female. This 

 family consists of two genera (Argas and Omithodoros), but they 

 are very closely allied, and perhaps should be united to form a 

 single genus. 



