OF WASHINGTON. 285 



have enumerated eight ; but this is less because of lack of obser 

 vation than of a deviation in the explanation of the principle of 

 articulation, as we shall see hereafter. 



The coxce are well developed, and are situated anteriorly 

 on the lateral border of the ventral surface. They are square or 

 oblong or trapezoid, or sometimes subtriangular in form, covered 

 by a darker-colored, hard chitinous plate, and are sometimes 

 strengthened by a chitinous ring at the insertion of the next joint. 

 They differ often in size as well as in form in the two sexes, and 

 some of them are armed with more or less long and prominent 

 spinous processes, or are cleft in the middle. These spines are, 

 as a general rule, more frequently found in the male than in the 

 female. 



In Amblyomma the male has the first and the fourth coxas armed 

 with a long spine ; the female has only the first coxa with a spine, 

 the others with tubercles. 



In Hyalomma the male has the first coxa cleft longitudinally ; 

 the other coxae are without any processes. 



The female has no tubercular nor spinous processes on any of 

 the coxaa. 



In Ixodes the male and female have only the first coxas pro 

 vided with a spine of varying size. 



In Dermacentor the male has coxa I cleft, while the fourth 

 coxa is enlarged to an immense size. 



The female with coxa I like the male, the fourth not en 

 larged, the third pair often with a small tubercular process. 



H ce map hy sails. The male has all coxae provided with spines, 

 the first the smallest, the others gradually increasing in size, the 

 last the longest. 



The female has on all four pairs small tubercular processes. 



Rhipistoma. Male and female coxas without any processes. 



Rhipicephalus. Male and female first coxas cleft, the rest un 

 armed. 



Boophilus. The male has coxa I cleft ; the shape of this coxa 

 is triangular ; the rest is unarmed. 



The female has on the first coxa a small tubercle ; all coxae at 

 their posterior border with a sharp, dark chitinous ridge. The 

 first coxas in both sexes are here drawn out in a sharp, long, 

 apophysis at their anterior border. 



