888 The American Naturalist. [October, 
ZOOLOGY. 
Parthenogenesis among the Acari of Feathers.—In a com- 
munciation to the Entomological Society of France, Dr. Trouessart 
states that he has observed a parthogenetic manner of reproduction in 
the plumicolous Sarcoptide under such conditions as to preclude the 
possibility of mistake. In 1888 Dr. Trouessart described an Acarian, 
Syringobia chelopus, which is found in the tubes of the feathers of 
Totanus calidris, a bird of passage through France in the Spring and 
Fall. A study of the life history of this species has developed the 
following facts. 
In the Spring little colonies of the Acarian are found in the tubes of 
the feathers of the migrating wader, evidently having wintered in those 
narrow quarters feeding on the pith of the feather. Their numbers 
are small rarely exceeding ten or twelve in each colony. The composi- 
tion of the colonies is variable, but taking 25 or 30 of the principal 
feathers of the wing together there will be found the following eleven 
forms. (1) Eggs with a shell; (2) Naked eggs; (3) Normal larve ; 
(4) Abnormal larvæ; (5) Normal nymphs; (6) Abnormal nymphs; 
(6) Sexually developed females or secondary nymphs ; (9) Abnormal 
females; (10) Normal males or heteromorphs ; (11) Abnormal males or 
homeomorphs. All of the forms are not found together in the same 
feather. The normal form and the abnormal form (which I have 
called syringobia) live in separate feathers, and the naked egg belongs 
to the latter form. The males in the abnormal series are very rare, only 
one or two for one hundred females in that series; while in the normal 
series the proportion is one male to three females. Neither normal 
males or eggs with a shell are found with the syringobial females. 
These lay naked eggs covered only with the thin hyaline membrane 
which forms the inner covering of the shelled eggs 
In a general way the syringobial form, is distinguished from the 
normal by its large cheliceres and by the thin, transparent skin over 
the posterior part of the body. The syringobial female is larger and 
more elongate than the normal type 
The skin left after the final salt, which transforms the syringobial 
nymph into an adult female, is totally wanting in the post-anal opening 
which corresponds to the copulatory pouch and which is perfectly plain 
in the secondary normal nymph or sexually developed female. 
The life-history as traced by Dr. Trouessart proceeds as follows: 
