60 



THE CLASS OF INSECTS. 



that of the young larva, and stand out fi-ec from the body. 

 The head is much smaller in proportion to the rest of tlie 

 body, and bent more upon the breast. 



The Larva (Fig. 62) 

 when hatched is about 

 five hundredths of an 

 inch in length. The 

 head is now free and 

 the antenniB stand out 

 free from tlie front. 

 Tlie thorax has greatly 

 diminished in size, 

 while the abdomen has 

 become wider, and the 

 limbs very long; and 

 the numerous minute tubercles, seen in the preceding stage, 

 have given origin to hairs. The dorsal vessel can now, for the 

 first time, be seen. AVlien in motion, the resemblance 

 to a spider is most striking. The flow of blood to 

 the head, and the return currents through the lacunar 

 or venous circulation along the side of the body were 

 easily observed. The vessels were not crowded with 

 blood disks, the latter being few in number, only one 

 Fig. 64. or two passing along at a time. Two currents, pass- 

 ing in opposite directions, were observed in the legs. 



Fig. G3. Side view of the head of the larva of Diplax Ijefoi'e the first moult, c, 

 deciduous tubercles terminating in a slender style; their use is unknown; they 

 have not been observed in the fall-grown larva, r, the compound eyes. 1, the 

 three jointed antenna;, the terminal joint nearly three times as long as the two 

 basal ones. 2, the mandibles, and also enlarged, sliowing the cutting edge divided 

 into four teeth. 3, maxilhe divided into two lobes : (/, the outer and anterior lobe, 

 2-jointed, the basal joint terminating in two sctre; and a, the inner lobe concealed 

 from view, in its natural po.'^ilion, by the outer lobe, <^ 4, the base or peiliccl of 

 the second maxilL-ie, or labium, the expanded terminal i>ortion being drawn sep.a- 

 rately; rf and «, two movable stout styles representing, jjerhajis, the labial palpi; 

 the lobe to which they are attached is multidentate, and adapted for seizing 

 pre}'; on the right side the two styles are appressed to the lobe, .r represents, 

 perhaps, the ligula; but we have not yet studied its homologies carefully: this 

 part is attached to a transversely linear piece soldered to the main part of the 

 labium, y, the Hth abdominal ring, with its pair of conical anal styles, z, the 

 last tarsal joint and iiair of long slender claws. 



Fig. ()4. The i)upa of Diplax, having rudimentary wings, in which the eyes are 

 much larger, and the legs much sliorter than in the I'ecently h."itched larva; in- 

 troduced to be compared with the young larva. Figs. 57-64, original. 



I 



