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PROCEEDINGS OF THE NATIONAL MUSEUM 



Vol. 68 



thumb; (in this variety of P. hwnanus one of the setae on the an- 

 terior side of the thumb is situated nearer the tip of the thumb than 

 the usual accessory spine, and this seta is in this instance decidedly 

 spinelike, hence apparently there are two anterior accessory spines) ; 

 outer posterior accessory spine very long, situated nearer the outer 

 margin of the thumb than the chief spine and extending beyond 

 the margin of thumb by over one-half its length; inner posterior 

 accessory spine the stoutest of all the accessory spines and about as 

 long as the chief spine. Femur III without indication of posterior 

 tubercle. Pleural plates similar to those of female except for plate 

 I which is smaller, more irregular in shape and less squarish. 



Length of medium-sized individual, 2.30 mm.; width, 0.70 mm. 



Type host and type locality. — By process of elimination the Cau- 

 casian race of mankind has become type host. No type locality. 



Fia. 7. — Ventral, ou rosTEnioit, view op end of left anterioh leg op male op 



PEDICULUS (TEDICULUS) HUMANUS LINNAEUS, TAKEN IN GERMANY 



This description is based upon a lot of 3 females and 3 males 

 collected at Eberswalde, Germany, by Doctor Krausse. By compar- 

 ing these specimens with the descriptions of the early entomologists 

 of Europe for the type of head louse found on white man the writer 

 is convinced that they really represent the P. humanus humanus of 

 Linnaeus. The variety stands out conspicuously among the pure 

 varieties of the head lice of mankind studied by the writer in several 

 respects. First, it is more slender, with somewhat shorter antennae, 

 the thoracic spiracles are decidedly larger in proportion to the size 

 of the body, the body setae are more numerous and nearly all of 

 them are peglike or spinelike and less than half of them are in 

 transverse rows, the chaetotaxy of the thorax is distinctive, and a 

 few other characters of minor importance are noted. 



