222 Mr Harrison, A preliminary account of the 
well-defined sub-mentum and mentum, the latter with rudimentary 
palps. In the Ischnocera, the mandibles are strongly developed, — 
but the maxilla is reduced to a conical lobe, and the labium is 
only rarely separable into sub-mentum and mentum. In both — 
sub-orders, as also in the Copeognatha, there is present a remark- — 
able hypopharynx, which consists, in its typical form, of a lyriform — 
chitinous sclerite lying in the floor of the mouth, with a pair of — 
. 
sclerosed glands lying below and behind it, from which tracheated — 
ducts run forwards and upwards, turn backwards and unite, the — 
common duct entering the sclerite. Running backwards from the — 
glands are two chitinous pedicels, which are tendinous in nature, 
and serve for the attachment of muscles. These structures, which 
would appear to have lost whatever function they once possessed, 
have been studied by Cummings (1913), who has shown that they 
can undergo very remarkable variation and specialisation. I have 
studied most of the types used by Cummings, and can confirm 
his work. 
As regards previous interpretations of the Anopluran mouth- 
parts, we have, as already stated, that of Enderlem (1904), who 
ee et 
—=-. 
finds labium, hypopharynx, and maxillae in the piercer-sheath ; — 
and that of Cholodkowsky (1903), who states that the embryonal — 
mandibles and maxillae disappear, and that the whole piercing 
apparatus is formed from the labium, which becomes internal in ~ 
position owing to a fold of the ventral integument of the head 
growing forward over it. Enderlein’s account is based entirely on — 
his belief that the Anoplura are Rhynchota, and he does not 
advance one tittle of evidence in support of his views that the 
structures which he names labium, hypopharynx, and maxilla are 
really homologous with the same structures of other imsects. His 
bare statement, and a vague reference to comparative anatomy, 
are apparently expected to convince us. But an examination 
of the rest of his comparative description does not serve to 
justify any unreserved acceptance of his statements. His ventral 
lamella of the pharynx is the buccal plate, the roof of the buccal 
cavity. His ‘fulturae’ are the diverging cornua of the same plate. 
His ‘dorsal lamella’ is the floor of the pumping-pharynx. His 
larynx—and if terminology must be borrowed from vertebrate 
anatomy, it might at least be applied to analogous structures—is 
the pharynx. He indicates the ‘mandibles’ as projecting freely 
into the buccal cavity in a figure (1905, p. 634, f 4) which he 
certainly has the grace to call ‘stark schematisiert,’ whereas these 
structures lie in the body-cavity, and have no connection with the 
alimentary canal. Enderlein has accurately described and figured 
the several structures lying in the piercer-sheath, as seen in 
dissection, but all the rest of his account, as well as his conclusions, 
may be dismissed without further consideration. 
