14 
W. L. WILLIAMS. 
sternite with a transverse guard at its anterior end. Penis be¬ 
tween the epimera of last hind legs and anus, extending over 
half this distance, conical in form, and bearing near its base an 
obtuse semicircular sternite. The young non-gravid female is 
distinguished from the male by the absence of genitals, copula¬ 
tion being effected through the anus, as in most acaria. The 
nympha and octopod larvae differ in appearance from the non- 
gravid female only in size, no genital system, either male or fe¬ 
male, being yet developed. 
According to Megnin, the six-footed larva is rarely seen, as 
it quickly moults. We have failed to find it except in the body 
of the gravid female. 
The Cytoleichus Sarcoptoides has its chief habitat in the air 
sacs of the gallinacese, especially in the common fowl. They 
have not been found outside the body nor in other parts than 
the air sacs and their communications : the lungs, bronchi and 
hollow bones. By reason of their comparatively large size they 
are readily discovered by the unaided eye, being observed upon 
the thin pellucid walls of the air sacs as small white particles, 
like grains of fine meal. At times, they are found somewhat 
widely scattered ; generally they tend to collect in groups. 
Soon after the death of the fowl and opening of the body, they 
tend to congregate in clumps within the deeper and darker re¬ 
cesses of the air sacs behind the kidneys, etc. Although they 
can in some cases be found in the hollow bones which com¬ 
municate with the air sacs, and in the bronchial tubes, they are 
not as a rule so readily found in these parts, and but rarely 
exist there in great numbers. They are readily picked up from 
the air sac walls on the point of a knife or needle, or easily 
washed off with a stream of water. They exhibit no power of 
attaching themselves to the walls of the sacs beyond that re- 
' quired to maintain their body weight. Neither do they possess 
the power of firmly attaching themselves to each other. 
Though they congregate in groups in the cadaver of the dead 
bird or when floating on a liquid, yet they are readily drawn 
apart, and unlike many acaria they do not appear to become 
