1914] Smith—The Development of Anopheles punctipennis Say ll 
Fourth Stage of the Larva. By the twelfth or thirteenth day 
the larva has increased in length to 4-5 mm., and it then shows 
_the signs of an approaching molt, the darkening of the head and 
collar and the widening of the latter. Molting is getting to be a 
critical process and a great many lose their lives in the act. They 
are conspicuously large and cannot protect themselves meanwhile. 
Sometimes the integument of the head does not separate off easily. 
One was seen in which the head had not molted for more than 
twelve hours after the rest of the integument had been shed. For 
a day or more before the third molt, the changes about to occur 
are evident. They consist of the appearance of the palmate, or 
stellar hairs, which are of use in clinging to the surface film (fig. 7). 
The body needs more support in its horizontal position. The 
palmate hairs (ph) appear on the third, fourth, fifth, sixth, and 
seventh segments of the abdomen, and may be seen projecting 
out from the segments for more than a day before the molting. 
They appear quite suddenly. At the same time the reddish adult 
eyes have become very conspicuous and are seen to be increasing 
in the number of ommatidia. 
After the molt, the maculation of the head appears to be different 
from that just after the previous molt. The pattern of the spots 
is the same, but the increased amount of pigment in the surround- 
ing integument prevents the spots from showing clearly. The 
buds within the thorax have become very prominent by this time 
and in addition to the respiratory siphons and the wings, we may 
see the projecting buds of the legs beneath, and of the halteres. 
In the head, which remains especially clear for several hours after 
each molt, we may see now the forming buds of the antennze 
(fig. 20), the main portion of the brain with nerves branching to 
the eyes, to the antennz, and to the digestive tube. Numerous 
muscles to the mouth parts, with their relations to the muscular 
lining of the integument, may be seen at this time also, as long as 
the integument remains transparent. Now, too, the clear, dark 
spots between the abdominal segments first become visible 
(figs 7): 
From about the fifteenth day to the twenty-second, growth is 
rapid, if plenty of food is available. The record of one larva in 
the laboratory was as follows: 
