346 NEW YORK STATE MUSEUM 
and in most of them the incisures are paler in color. On each 
side of the thorax is a triangular dark spot in the mature 
larva which marks the position of the developing tracheal gills. 
of the pupa. The head is nearly quadrangular, a little longer 
than wide, dark brown or blackish in color, heavily chitinized, 
with two approximated irregular black eye spots on each side 
near the lateral margin. 
The antennae are placed at the sides of the head toward the 
cephalic end, dorsad of and near the base of the fan. They are 
very slender, apparently three jointed, about one half as long 
as the width of the head. The first joint is twice as long as 
the others taken together, slender, flattened, and sometimes 
almost hyaline; cylindric at the articulation with the second. 
The second joint is very slender, cylindric. The third joint is 
a short pointed process at the apex of the second; and two 
Similar processes are usually to be seen at the articulation of 
the first and second. The fans are placed laterally at the 
cephalic end of the head [pl.34, fig.7]. Each fan consists of 
from 30 to 60 scythe-shaped rays (variable with the species); 
cilitate on the inner side, with longer setae at regular inter- 
vals [pl.34, fig.7, 8]. Each ray is widened dorsoventrally on 
about its basal one fourth, and, when spread, presents the 
appearance of the arc of a circle extending over the width of 
the fan near the base. The rays of the fan are borne on stout 
peduncles, to which they are articulated. The fans seem to be 
used in sweeping food into the mouth of the larva. When 
closed, the tips of the rays come just to the oral opening. The 
rays are folded when the larva is disturbed, otherwise wide- 
spread. The mandibles are placed ventrad of the fans and move 
in a horizontal plane. They are elongate, rather stout, brown, 
nearly twice as long as wide, furnished with teeth on the inner 
side near the apex, from two to four large, black teeth at the 
apex, and from six to 15 paler colored teeth behind these, grad- 
ually decreasing in size, excepting that the last two are usually 
stouter and larger than those immediately preceding. Tie 
stout apical teeth are difficult to count because, lying in differ- 
