structure of the mouth-parts in the Body-louse 219 
origin, these two views cannot be reconciled, and one must, 
perforce, take one side or the other. 
T am wholly with Cholodkowsky, whose view is not new, nor 
solely his own, but has been arrived at independently by Melnikow 
(1869), Borner (1904), Handlirsch (1903), and is supported by 
Fulmek (1907), Mjdberg (1910) and myself (1915). I propose to 
‘show, not only that the Mallophagasand Anoplura are beyond all 
question closely related, but that the Anoplura are distinctly 
nearer, in a great many features, to the Ischnocera, of the two 
Mallophagan sub-orders. 
The antennae of Anoplura have 3—5 articles, as have the 
Ischnocera, and are filiform, and borne laterally upon the sides of 
the head. In the Amblycera, the antennae are capitate, with 4 or 
5 articles, and are hidden in a groove beneath the head. In all 
three groups a sensory organ of precisely the same structure is 
carried in the same position distally upon the ultimate and 
penultimate articles. 
The legs of the three groups are similar in form, and differ 
considerably from those of most’ insects. The Amblycera have 
two equal divaricate claws upon a two-jointed tarsus, except in 
the Gyropidae, which have the claws remarkably modified. The 
Ischnocera are generally stated to have a two-jointed tarsus and 
two claws, except in the Trichodectidae, which have a single claw. 
This statement is quite wrong. The Ischnocera have only a single 
joint in the tarsus (though in some species of Trichodectes there is 
an indication of a second) and have in all cases only one functional 
claw. The so-called second claw was undoubtedly a claw to begin 
with, but is no longer connected with the flexing apparatus, is 
incapable of voluntary movement, and is, in many species of 
Philopterus, much reduced in size, while in Trichodectes it has 
disappeared. A remarkable intermediate condition occurs in the 
Anopluran Haematomyzus proboscideus, parasitic upon elephants, 
in which this degraded claw may be seen in transition from its 
terminal position to the preaxial place of a tarsal hair. The 
Anoplura in general have a single tarsal joint, and a single claw. 
In the Ischnocera meso- and metathorax are always fused ; in 
the Amblycera a distinct mesothorax is present in many genera ; 
in the Anoplura the thorax is quite undivided, except in Haema- 
tomyzus, which has a prothorax separated off. 
The abdomen consists in all three groups of nine segments in 
the adult, with evidence of at least two more in the larval stages 
(Harrison, 1915, p. 122). That of the Anoplura resembles certain 
Amblycera, rather than the Ischnoceran type. 
The alimentary canal is generally similar in all three. In the 
Ischnocera the crop is an asymmetrical diverticulum of the oeso- 
phagus. In the Amblycera there is a symmetrical dilatation of 
