structure of the mouth-parts in the Body-louse 223 
| Cholodkowsky, however, cannot be so lightly dealt with. He 
examined Pediculus embryos, both entire, and in sections, and 
he states quite definitely that the mandibular and maxillary rudi- 
ments fuse and disappear, that the labium alone forms the piercing 
apparatus, and that all other chitinous plates and splints appearing 
about the mouth are secondary structures. Apart from this 
general statement he attempts no detailed interpretation. Until 
Cholodkowsky’s ontogenetic work is either confirmed or refuted 
by renewed embryological investigation, the broad facts must be 
accepted. 
The following suggestions are on this account quite speculative 
in character, but are based on a considerable knowledge of Mallo- 
phagan mouth-parts. I assume that the close affinity between 
Mallophaga and Anoplura is sufficiently well proven. I suggest 
that the Anoplura show stronger points of resemblance to the 
Ischnocera than to the Amblycera. As there is no evidence as to 
the degree of relationship between the two Mallophagan sub- 
orders, the fact that the Anoplura favour one or the other is 
possibly not of very vital importance, if the two sub-orders are 
branches of a single stock. But it is possible that these sub- 
orders, which do differ markedly in certain respects, have branched 
off at different times from an original Psocid stock, in which case 
the resemblance of the Anoplura would have more significance. 
For our present purpose, however, the significance lies in the fact 
that the maxilla has almost completely disappeared in the Ischno- 
cera, a fact which agrees with Cholodkowsky’s statement of what 
happens with Pediculus. I am not prepared to believe that the 
mandible disappears, for I think that the structures which Ender- 
lein describes as mandibles in Haematopinus suis are reduced 
mandibles. The German author is certainly wrong in believing 
that they project into the buccal cavity, and he is again wrong m 
his homology for these structures in Pediculus, as what he calls 
mandible here is simply an optical section of a chitinous thickening 
passing almost completely round the head. But mandible-like 
structures do exist in the first larva of Pediculus (Fig. 7), and 
Fig. 7. Anterior portion of head of larva, to show mandibles. 
VOL. XVIII. PTS, V. & VI. 15 
