,»Ad cadaver ovis putridissimum, aquae stagnanti maxi- 
imam partem immersum, odore foetidissimum, individua 7 vel 8 
sono pipiente celerrime circumvolando congregantia, et in cada- 
veris parte supra aquam elevata interdum sedentia, die 16 Juni 
in Lapponia observavi, ova in cadavere sine dubio depositura.“ 
(Translation.) In Lapland, on the 16 of June, near a very putrid car- 
case of a sheep, the greater part of which was immersed in stagnant, most 
offensively smelling water, I perceived 7 or 8 specimens flying about in a circle ra- 
pidly, and emitting a piping sound, and sometimes alighting on the portion of 
the carcase above the water, evidently for the purpose of depositing their eggs. 
Objectors may urge that the presence of the flies in this 
case was merely accidental; that they were hovering over the 
carcase, and settling upon it for rest, and not for oviposition. 
Fortunately, besides the testimony of the expert Zetterstedt, 
we possess another, more detailed description of the method 
of oviposition of an Eristalis by the master of patient obser- 
vation and accurate description Réaumur (Mém. IV, p. 475). In 
Réeaunur’s case the egg is not deposited upon a carcase, but 
upon one of the tubs filled with stagnant water, which he kept 
in his garden for the sake of observing aquatic larvae. The 
preliminaries of the oviposition are described thus: ,When the 
water does not reach the edge of the tub, and its surface is 
8 or 10 inches lower, the fly, always on the wing, enters into 
the tub, and remains in it describing many circles just above 
the water; from time to time it dips the tip of its feet into 
the water; finally when this fly, ready for oviposition, has sut- 
ficiently examined the tub and the water, and ascertained that 
the place is suitable for its eggs, it alights on the inside wall 
of the tub, a few inches above the water. Then its begins to 
protrude its abdomen, the tip of which ends in a point bent 
towards the belly; it rubs this point against the wood; then it 
draws in the tip of the abdomen to make it protrude again 
very soon, and repeat the operation etc.* The ,describing many 
circles“® reproduces exactly the ,celeriter circumvolando* of 
Zetterstedt, and the fact that the eggs are deposited on the 
sides of the tub, and not dropped into the water, recalls the 
