346 NEW YOKK 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. The 

 stout apical teeth are difficult to count because, lying in differ- 



