142 MOSQUITOES OF NORTH AMERICA 
out on the surface of the water behind her, parallel to each other, not crossed as 
some observers state. A single row of creamy white eggs had been laid flat on 
the surface of the water and were kept in position by the two hind legs. . . . 
“ When the first row of eggs was completed she laid another row on the top of 
it, and then another on the top of that, and so on until the raft was finished. 
Then by a movement of the hind legs she tilted the raft so that the eggs stood 
on end.” 
In the genera Culex, Culiseta and Mansonia the egg-mass rests upon the sur- 
face of the water. The mass has a certain repellant quality, inherent, it seems, 
in a covering of delicate air-cells on the under surface. In the genera Urano- 
tenia and Lutzia the egg-boat is in part submerged, only the upper part of the 
eggs protruding from the water. Thus, Dyar states that in the egg-boat of 
Uranotenia sapphirinus the middle eggs are nearly half submerged. In the 
case of Lutzia bigotii, as observed by Jennings, the egg-boat is in large part 
submerged, only the apices of the eggs protruding above the water. The eggs, 
which are arranged in a double row, are remarkable in coloration ; the submerged 
portion is pale yellow with a golden luster while the exposed part is pale blue. 
The number of eggs and their mode of arrangement varies for the species, 
and to a certain extent within the species. The egg-raft of Lutzia bigot, just 
mentioned, is composed of about fifty eggs arranged in a double row. The eggs 
of Mansonia fasciolatus and M. arribalzage@ are arranged in a long, ribbon-like, 
double row with a gentle convexity upon the under side. Goeldi states that 
there are about 60 eggs in these egg-rafts but his reproductions of photographs 
of such egg-masses show from 70 to 80 eggs in a row, therefore 140 to 160 in the 
entire mass. Our Mansonia perturbans forms an egg-raft similar to that of 
Culex, that is, with the eggs in a number of rows forming an elongate mass and 
the under surface of the mass convex. In Culez, Culiseta and Uranotenia the 
egg-masses are elongate, and, on account of the convexity of the lower surface, 
the sides are somewhat upturned. 
Few exact data are available as to the number of eggs laid, even for the com- 
monest species. With reference to the common house mosquito, Culex pipiens, 
250-300 is generally given as the normal number, a statement to be traced back 
to Réaumur’s work. Our American observations are unsatisfactory, as a num- 
ber of species have undoubtedly been confused under the one name. Davis, in 
Illinois, found the number to vary from 120 to 309 in a count of ten egg-boats. 
Smith states that normally the number of eggs laid by Culex pipiens in a single 
raft is about 400 but that if the female is disturbed in the process there may be 
two or more smaller rafts formed. Goeldi (at Pard), in a count of two egg- 
masses of Culex quinquefasciatus found 225 and 270 eggs respectively and his 
pictures show that they are arranged in from 9 to11 rows. C.S. Banks, with the 
same species before him in the Philippines, found the number of eggs from 180- 
350, arranged in from 6 to 9 rows. In Culex territans two egg-masses counted 
by Knab contained respectively 105 eggs in six rows and 132 eggs in eight rows. 
A singular departure in the mode of egg-laying, or rather in the character of 
the eggs, has been recorded by Busck in Culex jenningsi, and this is probably 
shared by other bromelia-inhabiting species of Culex. In this case the eggs are 
