Packard.) 



370 



[January 22, 



body. The head is much smaUer in proportion to the rest of the 



body, and bent more upon the breast. 



8. The Larva (Fig. 5). When hatched it is about .05 inch in 



length. The head is now free and the antennas stand out free from 



the front. The thorax 

 // has gi'eatly diminished 



in size, while the abdo- 

 men hais become wider, 

 and the limbs very long; 

 and the numerous mi- 

 nute tubercles seen in 

 the preceding stage have 

 given origin to hairs. 

 The dorsal vessel can 

 now, for the first time, 

 be seen. When in mo- 

 tion, the resemblance to 

 a spider is most striking. 

 The nervous ganglia are 

 from one-fourth to one- 

 fifth as wide as the ab- 

 domen itself, and are 

 connected by two slen- 

 der commissures. The 

 flow of blood to the 

 head, and the return 

 currents through the la- 

 cunar or venous circula- 

 tion along the sides of 

 the body are easily ob- 

 served. The vessels were 

 not crowded with blood 

 discs, the latter being 

 few in number, only one 

 or two passing along at 

 a time. Two currents 



N, ventral cord ornervous ganglia; ur dorsal vessel, passino- in opposite di- 

 or "heart," divided into Its chambers. Theanal valves^ . '^ '■ '■ 



at the end of the abdomen, which open and shut dur- rcctions, were observed 

 ing respiration, are rejiresented as being open. Both :,, |] „ leo-q 

 of'the dotted lines cross the traclieas. x, net-work of o 



the tracheae, surrounding the cloaca. The young larva dif- 



fers remarkably from 

 the mature larva (which for the most part differs from the jjupa (Fig. 

 6) only in the smaller eyes and absence of the rudiments of wings), 



The larva just hatched and swimming in the water. 



