THE Hoc LovusE 673 
maxillae as the bristles lying within it. Graber (1872:138) distinguished 
in the mouth parts of Phthirius an upper lip, an under lip (proboscis), 
and a sucking tube formed possibly by the fusion of the mandibles and 
‘the maxillae and capable of protrusion from the proboscis, but he did 
not realize the true nature of the piercers and their sheath. He saw 
these structures extending far back in the ventral region of the head, 
and interpreted them as the retractor muscle of the proboscis. 
The next two in the long succession of publications appeared at intervals 
of ten years, and both dealt, one entirely and the other in part, with species 
affecting domestic animals. Strdbelt (1882, English trans. 1883:86) de- 
scribed very incompletely some of the structures surrounding the mouth 
openings of Linognathus vituli (Haematopinus tenuirostris) without seeing 
the real mouth parts, while Meinert (1891-92:58) used Haematopinus 
suis to illustrate his study of the mouth parts of Pediculus humanus 
and figured the different parts of the apparatus. Meinert called the 
whole structure the pharynx, distinguishing the anterior part of the 
stomodaeum proper as the epipharynx and the ventral sheath and piercers 
as the hypopharynx. 
A third decade passed before another contribution appeared, and then 
Cholodkovsky (1903:120) attacked the subject from a different aspect. 
Realizing the uncertainty pervading all the earlier literature—most of 
which had appeared before the application of section-cutting to investi- 
gation methods——as well as the urgent need of embryological studies to 
supplement the early work of Melnikow (1869:153), Cholodkovsky 
not only studied mature species of Pediculus and Haematopinus, but 
also many mounts and serial sections of different stages of embryos of 
two of the species infesting man. The result led him to believe that 
mandibles and maxillae are present in the early stages of the development 
of the germ band but disappear entirely before the escape of the young 
insect from the egg, and that the piercer sheath and its apparatus are 
formed from the labium alone. Melnikow (1869:153) had emphasized 
the relationship between the Mallophaga and the Pediculidae, and 
considered both as a family of the Rhynchota. Cholodkovsky agreed 
with the first part of this statement, but thought the two groups should 
rather be classed with the Orthoptera (particularly with Pseudoneuroptera), 
or, preferably, should be placed in a separate order by themselves, for 
which he suggested the name Pseudorhynchota. 
