130 Terminology 



backward between the coxae, then externally to the anal grooves toward 

 the posterior body-margin which they frequently attain. 



Anus situated in the median line posterior to the coxae ; the term applied for 

 convenience' sake to the external anal apparatus consisting of a more or 

 less evident ring within which are two laterally-moving valves. 



Anal grooves in Ixodes {Prostriata) curve around the anus in front and run 

 backward toward the posterior margin. Whereas, in most cases, the 

 grooves fuse in a semicircle in front of the anus ; in other cases they 

 form an ogive, they are then termed " ogival " (like a gothic arch) ; in some 

 species the grooves are not continuous anteriorly. 



In Metastriata the anal grooves round the anus behind, and in most cases 

 they run forward and outward toward the genital grooves, which they 

 may attain. In some cases they are continuous with a postero-median 

 groove from which they fork anteriorly. 



Plates are large dense armour-like chitinous structures occurring in Ixodes ^ , 

 not rising above the surface of the body (as do the shields, for instance, 

 in Rhipicephalus, etc.) ; the plates are bounded by the ventral grooves 

 above named, or by soft portions of integument. We distinguish 1 pre- 

 genital, 1 median, 1 anal plate along the median line of the body ; 2 adanal 

 plates to either side of the anal plate ; and 2 epimeral plates with indistinct 

 external border extending forward outside the genital groove to near 

 coxa IV. 



Plaques are small chitinized plates occurring, for instance, in some species of 

 Amblyomma, and situated ventrally in front of the festoons. (Fig. 135.) 



Shields (adanal and accessory) are salient chitinous structures occurring in the 

 males of Rhipicephalus, Boophilus and Hyalomma on either side of the 

 anus. A pair, close to the anus, are always present and are termed adanal. 

 There is frequently a second pair external to these, and known as accessory ; 

 they are well developed in Boophilus. 



Spiracle = the " peritreme," or " stigmal plate," etc., of various authors. A respira- 

 tory organ situated ventro-laterally posterior to coxa IV. It may be circular, 

 oval or comma-shaped, and shows a more or less central structure which we 

 term the macula — which may or may not represent a pore. The punctate 

 surface may be enclosed by a more or less broad " frame " of chitin which 

 is incomplete postero-dorsally in comma-shaped forms. The structure of 

 the spiracle is of use in classification. (Fig. 137.) 

 Legs : Coxae are the immovable portions upon which the movable articles are 

 articulated ; of the latter especially the first {trochanter) and last {tarsus) 

 articles are of importance in classification. All of these may bear spurs, 

 spines, or teeth in various situations noted in the descriptions. When 

 coxae are described as bifid, they bear two spurs and are deeply incised ; 

 when described as trenchant they have a knife-like margin. It is of 

 importance to note the manner in which the tarsi terminate : if they 

 taper, are humped, bear ventral spurs, etc. The length of the claws in 

 relation to the pads, or suckers {pulvillum), should also be noted. (Fig. 138.) 

 Punctations are circular depressions dotting the integument, and frequently 



