Art. 19 LICE OF THE GENUS PEDICULUS EWING 19 



closer inspection of his figures (pi. I, T. VII) shows that his variety 

 capitis has the abdominal segments more clearly demarcated, the 

 pleural plates pigmented, the neck region more distinct and the 

 thorax flatter than in his variety corporis. Although these charac- 

 ters are quite variable and not strictly reliable for separating most 

 of the body lice that are found on white people from the typical 

 European head louse, yet they do indicate that what he was dealing 

 with was a variety very similar in certain respects to the forms men- 

 tioned by others as the body louse of Europeans. 



Some of the American body lice are similar to the head louse of 

 Europe, others are similar to the Indian head-louse type, and yet 

 others show affinities with the body louse of Africa. In these forms 

 there are found almost all degrees of intermediate characters, be 

 they the shape of antennal segments, shape of neck region, chaeto- 

 taxy, size of thoracic spiracle, or any one of several other structures. 



Judging from the literature and from observations on many body 

 louse hybrids, the corporis of De Geer was a smaller louse than P. 

 humanus nigritarwn, and also it had the discal setae of the abdomen 

 more numerous and more peglike; the segments of the antennae 

 were hardly as long and were of more uniform width. 



It is highly probable that a race of P. humanus capitis spread to 

 the body from the head as the habit of wearing clothes developed 

 among the Caucasians. It is stated that some races of man when 

 they were yet uncivilized had no body lice, but when a certain amount 

 of clothes-wearing was practiced and contacts with w^hite man were 

 made they became infested with body lice in addition to the head 

 lice. 



PEDICULUS (PEDICULUS) HUMANUS ANGUSTUS Fahrenholz 



1915 Pcdiculus capitis amjustus Fahrenholz, Zeit. f. Morph. u. Anthro., 



vol. 17, p. 597. 

 1915 Pediculus capitis marginatus Faheeniiolz, Zeit. f. Morph. u. Authro., 



vol. 17, p. 599. 

 1917 Periculus humanus marginatus Fahrenholz, Zool. Anz., vol. 48, p. 87. 

 1917 Pediculus humanus chincnsis Fahrenholz, Zool. Anz., vol. 48, p. 87. 

 1917 Pediculus corporis angustus Fahrenholz, Zool. Anz., vol. 48, p. 88. 



1919 Pediculus humanus, race capitis Nuttall (pax't). Parasitology, vol. 



11, p. 334. 



1920 Pediculus humanus, race capitis Nuttall (part). Parasitology, vol. 



12, p. 152. 



Female. — Only hybrid or racially impure females observed. 



Male. — Head longer than broad, yet with poorly developed neck; 

 forehead long, two-thirds as long as broad and with sides much more 

 heavily chitinized than the temples; postocular tubercles low. An- 

 tennae (broken in two specimens observed and last two segments 

 wanting) of the type of corporis', first segment slightly broader than 

 long and broadest at its base ; second segment twice as long as broad 

 and broadened distally; third segment one and a half tunes as long 



