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ON FAHRENHOLZ’S PURPORTED NEW SPECIES, 
SUB-SPECIES AND VARIETIES OF PEDICULUS. 
A CRITICISM OF METHODS EMPLOYED IN DESCRIBING ANOPLURA. 
By GEORGE H. F. NUTTALL, Sc.D., F.R.S. 
(From the Quick Laboratory, University of Cambridge.) 
(With 2 Charts.) 
CONTENTS. 
Introduction ....... 
I. Fahrenholz’s evidence in support of the validity of his species, sub¬ 
species and varieties of Pediculus . 
II. Evidence disproving the value of the characters whereby Fahren- 
holz distinguishes the before-mentioned forms of 
Pediculus ........ 
(a) Measurements of Pediculus . 
(b) Morphology of Pediculus . 
(c) Pigmentation in Pediculus . 
Proof that there is no constant relation between the degrees 
of colouration shown by different parts of the exo¬ 
skeleton in pigmented Pediculus humanus 
III. Supplementary Note upon the Synonymy of Pediculus humanus. 
Conclusions ....... 
References 
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INTRODUCTION. 
The object of this paper is to draw attention to certain grave sources of error 
underlying the present mode of differentiating Anoplura 1 arid more especiallv 
species of the sub-order Siphunculata, I am unable to say if the criticisms 
herewith advanced apply equally to the methods employed in differentiating 
members of the sub-order Mallophaga, because I am not familiar with the 
latter group, but the two sub-orders mentioned are in many respects so closely 
allied that it appears difficult to avoid the suspicion that the considerations 
herein contained may apply equally in both cases. 
Eahrenholz is a recognized authority on Anoplura, he has dealt with the 
group in Das Thierreich, and consequently is in a position to mislead others who 
may concern themselves with the study of these ectoparasites. 
1 The order Anoplura Leach, 1817, includes two sub-orders: Mallophaga and Siphunculata 
(see Nuttall, Parasitology, xi. 332). 
