THE BIoLoGy oF THE CHRYSOPIDAE 1297 
1872) and Tichomirowa (1890). The embryological observations made 
in the course of the present studies are not included in this account. 
The chief point observed in the embryology which has not been 
described, it is believed, is the turning or partial turning of the embryo. 
The germ band develops on the venter of the egg, with the area destined 
to be the end of the abdomen extending around the posterior pole of 
the egg and part way up the side of the dorsum. At thirty hours the 
abdomen can be seen clearly in this position on the basal dorsal part 
of the egg. As development proceeds, the abdomen shortens and is 
drawn up in a fold at the posterior pole. As the dorsum of the embryo 
continues to envelop the yolk mass, the contracted abdomen pushes for- 
ward and comes to lie on the venter of the egg, reaching nearly to the 
tips of the jaws. The dorsum of the embryo has by that time enveloped 
_ the yolk mass and les next to the chorion. This is the position of the 
embryo at hatching. 
The large black ocellar areas appear very prominent in eggs ready to 
hateh, at the anterior end of the egg on each side of the midventral line. 
There is a lateral indenture of the chorion on each side extending nearly 
the length of the egg. There is a series of three or more somewhat tri- 
angular, very dark to black, bars at the sides. The egg burster can be 
seen as a narrow black line between the eyes in the midventral line. 
There is considerable variation in the length of the period of develop- 
ment within the species. Temperature is undoubtedly the most impor- 
tant factor, as this variation is between different batches of egos and is 
only slight in the same group. Eggs 
laid in the late fall or early spring were 
found to be the longest in development. 
The longest and the shortest records of 
embryonic development for a few spe- 
cies studied were: for Chrysopa oculata, 
from 5 to 12 days; for C. nigricornis, 
from 4 to 7 days; for C. quadripunc- 
tata, from 4 to 6 days. 
Hatching 
One ean readily ascertain when an 
ege will hatch by the distinctness with 
which the egg burster appears. Just Fig. 155. EGGS OF CHRYSOPA 
7 oF G JLATA 
before hatching, it is dark or black and . Slade 
: : A, Ventral view of egg ten 
one can searcely tell whether it is minutes sbetoue hatching, See ae 
s . : the e urster (s) in position ; 
through the chorion or just beneath it. Dorsuin of an efE ready to hatch 
