358 
INSECTA, 
sively confined to Birds. Their head is usually large, sometimes 
triangular, and at others forming a semicircle or crescent, and fre- 
quently presenting angular projections. It sometimes differs, like the 
antennae, in the two sexes. I have perceived, in several, two simple 
approximated eyes, on each side of the head. According to the obser- 
vations of M. Savigny, communicated to me by himself, these animals 
are provided with jaws, each of which has a very small palpus, hidden 
by the lower lip, which has also two organs of the same description. 
They have moreover a kind of tongue. 
M. Leclerc de Laval informs me that he has found parcels of fea- 
thers in their stomach — he thinks that they constitute their only food. 
De Geer, however, assures us that he has found the Pediculus of the 
Fringilla coelebs filled with recently imbibed blood. It is Avell known 
that these Insects survive but a short time on dead birds. When 
thus situated, they are observed to wander over tlieir plumes with 
much anxiety, those of the head and the vicinity of the beak espe- 
cially. 
Rcdi has also represented a great number of species of this sub- 
genus. 
The mouth of some is situated near the anterior extremity of the 
head. The antennae are very small, inserted laterally, and at a dis. 
tance from the eyes *. 
In the others, the mouth is nearly central ; the antennae are placed 
close to the eyes, and their length about equals half that of the 
head f . 
The celebrated professor Nitzsch has profoundedly studied the in- 
ternal as well as external organization of these animals, as may be 
seen by referring to his paper on the Epizoic Insects, in the Magasin 
der Entomologie of M. Germar. The genus Pediculus, properly so 
called, or that whose species are provided with a sucker, is arranged 
by him with the Epizoic Hemiptera. The Ricini of De Geer and 
others, or the Nirmi of Hermann, Jun., that is to say, the species fur- 
nished with mandibles and jaws, are referred to the Orthoptera, and 
collectively designated by the term Mallophaga. Two genera of this 
division approach the preceding ones in the circumstances of living 
on the Mammalia — such are Trichodectes and Gyropus. In the 
first the maxillary palpi are null or indistinct, and the antennae fili- 
form, and composed of three joints. The species of this genus are 
found on the Dog, Badger, &c. In the second the maxillary palpi 
are apparent, and the antennae, thicker towai’ds the end, consist of 
four joints. The mandibles have no teeth ; there are no labial palpi, 
and the foiir posterior tarsi have but a single terminal hook. These 
last characters distinguish it from another genus, also furnished with 
* Pediculus sterneE hirundinis, L. ; De Geer, Inseet., VII, iv, 12 ; — Fed. corvicora- 
cis, L. ; De Geer, Ib., ii ; — Ricinus fringillcc, De Geer, Ib., 5, 6, 7 ; — Ped. tinnun- 
ctdi, Panz., Ib., xvii. 
■f Ricinus gallina, De Geer, Ib., 15 — on the Cock, Partridge, and Pheasant; — 
R. emherizce, De Geer, Ib., 9 ; — R. mcrgi, De Geer, Ib., 13, 14 ; — R. canis, De Geer, 
Ib., 16; — Pediculus pavonis, Panz., Ib. xix ; Lat., Hist. Nat. des Fourm., 3S9, xii, 
5. See also Panz., lb., pi. xxv — xxiv. His Pedicidus ardea, XVIII, appears to be 
the same as the Ricin du plongeon, De Geer, IV, 13. 
