150 
Purported New Species, etc. 
are rendered visible even in balsam-mounted specimens! Fahrenholz merely 
overlooked existing structures because they were unpigmented. Conversely, 
by raising pigmented lice on white backgrounds, all of Fahrenholz’s specific 
characters may be made to disappear. 
Nearly all of the before-mentioned structures in Pediculus are illustrated 
in Parasitology, xi. p. 220, PI. X, figs. 1 and 2 (pigmented and unpigmented 
specimens raised on black and white respectively), pp. 281 et seq., figs. 2, 3. 
Others will be considered shortly in papers dealing with our studies on the 
anatomy of the insect. 
It is obviously fatuous for Fahrenholz to describe colour differences in 
balsam-mounted specimens of lice derived from various races of man ( u P. 
capitis angustus ” and “P. capitis maculatus ,J ). 
How much he was misled by preconceived notions regarding the different 
appearances observable in P. humanus, is further exemplified bv the circum¬ 
stance that when he found typical P. humanus race corporis in the Hamburg 
Museum collections bearing a label stating that they came from negroes, he 
considered their origin as “ very doubtful.” He would not believe that negro 
clothes-lice could be similar to those of Europeans, hence there must have 
been an error in the labelling (see p. 140). I have many hundreds of specimens 
which prove that body-lice from negroes and whites are identical in appearance. 
Proof that there is no constant relation between the degrees of colouration shown 
by different parts of the exoskeleton in pigmented P. humanus. 
The following observations were made by me with a view to determine if 
in a series of more or less pigmented specimens the colouration of the various 
parts follows any uniform law. 
Pleurae 
• Thorax sides 
Dorsal bands 
Frons 
Sternal plate 
Genital plate 
Chart II. Recording the variation in pigmentation shown by 20 selected Pediculus humanus 
race capitis, <$$, arranged in accordance with the degree of pigmentation shown by the genital 
plate which is darkest ( i.e . Grade 5) in specimen 1 and palest in specimen 20, as indicated by 
the heaviest line among the curves. « 
From several hundred capitis <$<$ (Lot 252, well-preserved), collected from 
a negro’s head in Tropical Africa, 20 specimens were chosen which showed 
various degrees of pigmentation when viewed by davlight whilst immersed 
in alcohol in a dish. A scale giving seven grades of colour from blackish brown 
