220 THE UNIVERSITY SCIENCE BULLETIN. 



setae, about equal to tibia in length. Second legs; tarsus equal to tibia, 

 both, together about as long as femur. Third legs with femora, but 

 slightly flattened, tarsus nearly as long as femur and tibia together, 

 clothed with set^, these longest at the joint, becoming much shorter 

 distally. Colour very transparent. A median grayish line on thorax." 



Third Ins tar. 



"Length, 2 mm. Width, 1 mm. Head as before. Eyes a little more 

 than one-fifth the head-width in width. The wing-pads first appear; 

 about three-fifths the length of thorax, sparsely hairy. Thorax one- 

 half as long as wide. Abdomen as before, fringed on the sides by rather 

 long setae, the posterior angles with conspicuous tufts. Ventral surface 

 sparsely pilose. 



"Tarsi all 1-jointed. The whole first leg about equal in length to the 

 femur of second leg. Tarsus about three times as long as broad, termi- 

 nated by a sharp spine. Second legs slender; tarsal claws as long as 

 tarsus, other joints as in third leg, all feebly setose. Third legs; tarsus 

 1% times the tibia, the latter equal to femur. Tibia and femur together 

 about equal to femur of second leg. Abdomen strongly truncate." 



Fourth Instar. 



"Length, 3mm. Width, 1.2 mm. Very much more pigmented and 

 less transparent than previous instars. Posterior margin of head, pos- 

 terior angles of eyes, and posterior margin of thorax fuscous. Anterior 

 margin of thorax and inner edge of wing-pads with rather dense 

 brownish-black hairs. These together with the pigmented posterior mar- 

 gin of the thorax form a square; a median patch of brown hair joining 

 the band on the anterior margin. General surface of thorax smoky 

 brown with narrow median clear line, and a paler transverse band in 

 the middle. Head pale brown with darker shading on vertex. Whole 

 dorsal surface of thorax and abdomen sparsely hairy, the abdominal 

 segments faintly indicated by transverse brown stripes. A median longi- 

 tudinal white stripe one-third the body-width in diameter runs the length 

 of the dorsal surface of the abdomen. Within this is a series of large 

 pale brown blotches, one on each segment, the third and fourth of these 

 with a distinct crescent of chestnut brown, marginal third of abdomen 

 smoky, fringed with cilia, but these less conspicuous because of the 

 general hairiness of the body. The wing-pads hardly extend beyond the 

 thorax. 



"Tarsi all 1-jointed. First legs as before. Second leg with femur 

 as long as width of head, equal to tibia and tarsus together. Claws 

 one-fifth longer than tarsus. Third leg with tarsus equal to width of 

 head, feathered with dense hairs. Antennae one-half of the length of 

 tarsus of first leg. Interorbital space two-thirds the width of head, and 

 equal to three-fourths the length from vertex to tip of beak." 



Fifth Instar. 



"Length, 3.8 mm. Width, 1.4 mm. Dorsal marking as in previous 

 instar, but more intensified. The two median dark brown marks of third 

 and fourth abdominal terga oblong, surrounded by a larger oblong one 

 of smoky brown. Hairy covering of wing-pads and thorax conspicuous, 

 the median patch of the anterior border extending more than one-third 

 the length of thorax down the median axis. Wing-pads extend half way 

 to third abdominal segment. Beak brownish, with short pubescence. 

 Legs pure white, antenna no larger than before, but fringed with short 

 cilia. Tarsi of first two legs one-jointed; those of third leg two-jointed, 

 otherwise legs as before. 



"In comparing the various larval stages one is struck by marked in- 

 crease in the size of the eyes relative to the size of the head as de- 

 velopment proceeds. Another point is of great theoretical interest. As is 



