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American Midland Naturalist Monograph No. 1 



species, as well as in others of the same genus, the characters of the mammil- 

 lae may be less definite or distinct when the ticks are fully fed. Depleted 

 specimens show the mammillae closer together and their elevation is at a max- 

 imum. The individual mammillae are then at their best as characters and show 

 clearly the true shape and markings, and the folds and grooves are either 

 normal or exaggerated. The length and width of the tick are but little in- 



Fig. 28. Male of Ornilhodoros iuricaia (Duges) on the left, and male of O. parken 

 Cooley on the right. 



