2 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.68 



hensive treatment of the genus for the whole world could be under- 

 taken, but lack of sufficient material from the Old World made this 

 consideration impossible. After long delay the want of sufficient 

 material even from the New World has made it necessary to reduce 

 decidedly the scope of the present paper. 



As already said, the early entomologists held that each of the races 

 of mankind harbored a distinct form of Pediculus. It has remained, 

 however, for Fahrenholz (1913, 1915), alone of the living entomolo- 

 gists, actually to demonstrate, in certain instances, according to the 

 viewpoint of the present writer, that there are distinct forms of 

 Pediculus for certain racial units of mankind. This German scien- 

 tist, however, has gone to the extreme of recognizing in one instance 

 as many as three distinct types of Pediculus for a single primitive 

 race of man. 



It is the intent of the writer not only to review in this paper much 

 of the work of Fahrenholz and others, but to give what he thinks is 

 the proper taxonomic arrangement of the American members of the 

 genus and also to elaborate in more detail some ideas in regard to 

 the significance of host relationship set forth in a preliminary note 

 published in Science (Ewing, 1924). 



THE GENUS PEDICULUS LINNAEUS AND THE NAME OF ITS 

 TYPE SPECIES 



The genus Pediculus was established by Linnaeus in the tenth 

 edition of his Systema Naturae, page 610. His diagnosis follows: 



Pedes VI, ambulatorii. 



Oculi II. 



Os aculeo exserendo. 



Antennae lougitudine thoracis, 



Ahdomen depressum sublobatiim. 



In this genus Linnaeus placed not only the sucking lice of man but 

 a large number of other lice, chiefly from domestic animals. Also 

 he did not at the time of the publication of the tenth edition of his 

 Systema Naturae differentiate between the head louse and the body 

 or clothes louse, including both under his Pediculus humanus. In 

 his twelfth edition Linnaeus does differentiate between the head 

 louse and the clothes louse, but he speaks of them as varieties 1 and 

 2, these designations having no validity according to modern rules 

 cf nomenclature. The first one to use varietal names for the two 

 forms of Pediculus was De Geer, who in 1778 called the head louse 

 variety capitis and the clothes louse variety corporis. These are the 

 designations by which both of these forms have been frequently re- 

 ferred to in recent literature, yet, of course, the name humanus Lin- 

 naeus must have priority over one or the other of them. It should 



