ORDER ANOPLURA, OR SIPHUNCULATA 215 



{Abdomen broad ; first pair of legs much slenderer than the others 

 = Phthirius. 

 Abdomen elongate ; all the legs equally robust = Pediculus. 



'Legs with a triangular pretarsal sclerite ; all the legs equally 

 robust ; eyes vestigial ; lateral margins of abdomen festooned ; 

 abdominal segments with a single transverse row of short 

 hairs = Hamatopinus. 



Legs without pretarsal sclerite ; the first pair more slender than 

 the others ; eyes absent = 9. 



{Abdominal segments well chitinised ; lateral margins of abdomen 

 festooned ; hind legs stouter than middle legs = 10. 



Abdomen soft, not festooned ; hind legs not stouter =11. 



'Abdomen with transverse rows of long stout hairs, most of the 

 segments subdivided = Polyplax. 



Abdomen with some rows of long, flat, scale-like hairs ; sides of 

 segments 3 to 6 produced dorsally and ventrally into a spur 

 serrated at tip = Hoplofileura. 



(Abdominal segments with two or three transverse rows of long 

 dense hairs ; stigmata remarkably large ; head tapering. 

 = Trichaulus. 

 Abdominal segments with one transverse row of hairs =12. 



Abdomen elongate, its lateral margins smooth and unarmed ; 

 stigmata very small, not prominent = Hcemodipsus. 



Abdomen broader, its lateral borders with a strong spine behind 

 the stigmata, which are of moderate size and prominent 



= Solenoptes. 



Genus Pediculus. Piaget admits three species, of which 

 two, P. capitis Leach and P. vestimenti Leach, are human 

 parasites. 



Pediculus capitis is known as the head-louse, but though 

 its favourite home is the scalp, it and its eggs are frequently 

 found on other parts of the body and in the clothing. 

 Pediculus vestimenti is the body-louse. The two species are 

 difficult to distinguish. P. capitis is smaller ; the abdomen 

 consists of 7 segments, has its sides festooned, and is beset 

 with hairs ; the " thumb " of the tibis carries a spine. P. 

 vestimenti is larger ; the abdomen consists of 8 segments, is 

 not deeply festooned at the sides, and is not hairy ; the 

 "thumb" does not always end in a spine. The "bite" of 

 P. vestimenti is said to be very much more irritating than 

 that of P. capitis. According to Andrew Murray, the 

 different races of men have their corresponding races of 

 Pediculi, the latter differing one from, another, not merely 



