39 
So far as known, this species is confined to pigeons, and there seems 
no danger of their being transmitted to other fowls with which they 
may associate. 
Piaget states that he has found the females astray upon a Sulci alba, 
upon a Totanus glottis and upon a Charadrius minor, only in the last i 
the appendages of the clypeus wanting ; the last segment had the lobes 
more acute and the dimensions were less. 
Denny described, under the names of Nirmus claviformis, what appears 
to be the young of this species, though he gives measurements for males 
and females, which would seem to indicate that he was able to see the 
sexual organs. In all the specimens we have examined that agree with his 
figure and description of this form we have been unable to discover the 
genital organs, which makes„it appear that they are immature, and they 
are in all cases associated with the baculus, with which they seem to 
agree in all structural characters. The body is shorter, the markings 
less distinct, and the rudiment of a trabecula is more prominent than 
in the adults. 
It seems best, therefore, at least till well marked males and females 
can be found, to consider these as immature baculus. 
Piaget does not discuss this matter, but in his index to the " Les 
Pediculines" he gives N. claviformis as a synonym of L. baculus. . 
THE SQUALID DUCK LOUSE. 
(Lipeurus squalidus Xitzsch.) 
According to Denny, this species was referred to by Fabricius under 
the name of Pediculus anatis, and it seems extremely 
probable that it was referred to under other names by 
many of the early writers, since it is so common on 
many species of ducks that it is hardly possible that it 
should have been entirely overlooked. The first defi- 
nite reference to it, however, is the description by 
Nitzsch in 1818; and, more fortunate than some of the 
related species, this has been allowed to hold in all 
subsequent works, and so far as we know there are 
no synonyms for its specific name. 
It is a very abundant and common species and oc- 
curs on a great many different species of ducks, both 
wild and domesticated ; indeed, so generally does it oc- 
cur on the different species of the genus Anas and re- 
lated genera that we may almost say that it is common 
to all species of the family including the ducks. 
It is quite characteristic in appearance, and not 
likely to be confused with other speSies on the same 
birds. It is about 4 millimetres (one-sixth inch) in 
length, elongate in form, and of a light yellowish color, 
with dark border to the head, thorax, and abdomen. ^^""^h^u * 
