216 Prof. J. C. Schjédte on Phthiriasis, and 
favourable to suction.’—Die Hautkrankheiten durch anatomische 
Untersuchungen erliutert, Berlin, 1848, p. 274, 279. 
This view, which had already gained so much attention by 
the influential support of Erichson, has recently again been main- 
tained in the strongest terms, in two treatises, by Dr. Leonard 
Landois in the ‘ Zeitschrift fiir wissenschaftliche Zoologie,’ Feb. 
1864, In the first paper, on the anatomy of Phthirius nguinalis, 
he expresses himself in the following manner :— 
« The organs of the mouth are situated in the foremost part of the 
head, mostly underneath. They consist of an haustellum (‘‘ promus- 
cis,” Kirby), which altogether has a length of 3, millim. On this I 
observed, first of all, a labrum longitudinally divided into two parts, 
which forms the upper part of the haustellum, and which proceeds 
from the middle part of the head. Near the root of the haustellum the 
two halves of the labrum diverge, having a width of =; millim. each, 
and ending in a continuation bent inwards. Viewed as a whole, the 
labrum presents the shape of a bottle, of which the greatest width, 
near the bottom, is ~; millim., whilst the narrowest part (the neck of 
the bottle) only measures 1; millim. in width. Each half of the la- 
brum carries on its foremost extremity a pair of excessively slender 
small hooks, which are biarticulated and turned outwards, diverging 
from one another ; these hooks consist of chestnut-brown, transparent 
and hard chitine. Underneath the labrum, not far from its point, 
two horizontally-working mandibles, true organs of biting, are 
placed in a transverse position ; they consist of a close-grained trans- 
parent chitine of a yellowish tint, along the lower edge shining brown. 
They are ;4 millim. long and), millim. broad. There are certainly no 
palpi to be found. My description and figure prove that the organs 
of the mouth in Phthirius correspond very nearly (except with 
regard to palpi) with the description of the same parts in P. capitis 
and P. vestimenti given by Erichson and G. Simon; and the last- 
mentioned author is no doubt quite right when he says, jokingly, 
that the common people know better that lice “ bite” than the 
naturalists, who take them to be sucking parasites. This point de- 
serves, in a high degree, the attention of systematic authors, who 
have hitherto persisted in separating lice “with sucking organs 
of the mouth”’ from their congeners “with a mouth organized for 
biting” (Ricinus, Mallophaga), an arrangement first proposed by 
DeGeer and afterwards further developed by Nitzsch and Latreille.”’ 
(Vide the periodical quoted, vol. xiv. no. 1, pp. 4 & 5, tab. v. fig. 2.) 
In the second paper alluded to, containing historical and 
critical investigations concerning phthiriasis, the author expresses 
himself, if possible, in still stronger terms :— 
«The occurrence of lice underneath the skin can only be explained 
by a number of them eating their way through the skin in one and 
the same place. his is to be understood literally ; for the lice are 
not, as was formerly generally supposed, provided with sucking-or- 
