51 
LOUSE OF DUCKS. 
(Trinoton luridum Nitzsch.) 
Eedi seems to have been the first to give mention of this very com- 
mon species, it being figured in the Exper., PI. XII, as the louse of the 
Teal. It is also figured by Albin (PI. 4G) under the same common 
name as quoted by Denny. Nitzsch described it in 1818 under the name 
£iven above, and the species has been fortunate 
enough not to have received any other designation 
since, although it hasbeen mentioned in most of the 
works referring to the parasites of domestic fowls or 
the parasites of birds. It is a very common species 
and occurs on a great many different species of ducks, 
so that it is unnecessary to try and enumerate the 
hosts. So far as we have seen or can learn from rec- 
ord, however, it is not known to occur en birds outside 
of the duck family (Anatidcc). 
Its nearest ally is the goose louse, to be mentioned 
next, and it is easily distinguished from that by the dif- 
ference in size and the more distinct markings in this 
species. The markings are shown in the accompany- 
ing figure, their distribution on the head, thorax, and 
abdomen being clearly indicated ; the abdomen is a fig. 38.— Trinoton iur%. 
trifle narrower and the sides a little more parallel dum - < 0ri s inal) 
than in some specimens observed. It is 4 to 5 millimetres in length. 
LOUSE OF THE GOOSE AND SWAN. 
{Trinoton conspurcatum Nitzsch.) 
This species was evidently recognized at an early date, and is said to 
be mentioned by Sulzer under the name of Pediculus anseris. Nitzsch 
described it in 1818 under the name which has been universally adopted 
since, and it has received frequent mention since that time. It is very 
similar to the Trinoton luridum, but may generally be easily separated 
by the more diffuse coloring and its larger size, being 6 millimetres (3 
lines according to Denny) in length. The two species are not known to 
infest the same kinds of birds. This species occurs on a number of 
species of geese and swans, and on one gull; according to Denny on the 
common domestic goose, on the Larus can us. and Ci/gnus bewickii : on 
Cygnus olor, according to Burmeister ; on C. musicus and olor, according 
to Piaget; and on Anser ruficollis, according to Grube. 
While the Trinoton luridum we have found to be rather common in 
America, the conspurcatum has not been met with, but the opportunities 
for examining geese have been limited. 
