a2 
THE LITTLE RED SWAN-LOUSE. 
(Docophorus cygni Denny.) 
Notwithstanding the apparent abundance of this species it does not 
appear to have been described before 1842, when it was described and 
figured by Denny (Monog. Anop. Brit., p. 95, Pl. 1, Fig. 1), but ac- 
cording to this author it was figured by Redi (Exper., Pl. 1x, fig. inf.), 
which would earry its recognition back 200 years. It is common on 
both the wild and domesticated swans, and Denny states that he has 
received it from the bean goose. 
It is a millimetre in length, of a robust form, the 
head decidedly rounded in front, except at the ex- 
treme tip, where it is slightly excavated. In color 
the head, thorax, and legs are bright reddish brown, 
while the abdomen is white in the center and dark 
brown at the sides, the brown occupying hard plate- 
like portions at the side of each segment. 
Rick Pacis: The form and the distribution of these plates are 
cygni. (Original.) Shown in the accompanying figure. 
CHICKEN LOUSE. 
(Goniocotes hologaster Nitzsch.) 
This common species of the domestic fowl was recognized by DeGeer 
and by Nitzsch. It has been generally confused with another form, or 
rather another larger and perhaps more common form has been gene- 
rally accepted by English and American writers as the hologaster, this 
being due to the description and figure given by Denny, who does not 
seem to have seen the true hologaster, but described for it, according to 
Piaget, an immature specimen of the larger species since described as 
Goniocotes abdominalis Piaget. 
The hologaster is only about one millimetre in length, whereas the 
abdominalis, or Denny’s hologaster, is about three millimetres. In general 
form the species is somewhat similar, the hologaster being less con- 
stricted at the thorax and more regularly tapering to the end of the 
abdomen. The head is more nearly quadrate; the abdomen not so 
conspicuously marked, the incurved margins of the segments not ex- 
tending so decidedly upon the disk and presenting the distinct lines 
seen as a border to the fascize in abdominalis. 
CHICKEN LOUSE. 
(Goniocotes abdominalis Piaget.) 
This is probably fully as common as the preceding species. As 
already stated, it isthe form which has been commonly referred to in 
