316 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



seven.* Tlie first joint appears to be without hairs, the second with two 

 hairs, the third with one short hair, the fourth with two hairs, tlie fifth 

 with one or two hairs, the sixth with one or two hairs, the seventh with 

 one or two hairs, and the eighth with six or eight hairs, two or three of 

 them longer than the otliers. All the hairs are proportionately 

 much shorter and more slender than in the larva. When at rest the an- 

 tennai are held in tiie position shown in fig. 26. The two spines directed 

 backwards on the front between the bases of the antennae are larger and 

 better developed than in the larva. The antenna is 290 /^ to 310 /^ in 

 length without including the terminal hairs. 



The very slender " 6eafc" is composed of four very long and very slen- 

 der chitinous setae, and often attains a length considerably greater 

 than that of the insect. As these are of internal origin they will be 

 more fully described further on. 



The structure of the thorax is essentially the same as in the larva. 

 The shallow grooves extending from the spiracles to the spiracular 

 emarginations are more marked. In these grooves are a number of fine 

 pores which secrete a white waxy, filamentary and powdery substance 

 which seems to serve the double purpose of keeping a passage open to 

 the air, but closed to foreign substances, and to hold the insect in place. 

 Whenever the insect is removed four white marks remain on the leaf or 

 bark to mark the position of these spiracular grooves. At the termina- 

 tion of each groove are the three spines as described in the larva. Their 

 function is unknown. The insertions of the legs are as in the larva,— 

 and we may add, between the sternum and episternum. 



All six leg.t are of almost precisely similar structure, (fig. 326), except 

 the coxae of the anterior pair may be a little shorter than the others. 

 The coxa is quite large, about twice as long as thick, and furnished 

 with about two hairs. The trochanter is very small, triangular, and im- 

 movably united to the femur. It bears one very long spiny hair. The 

 femur is about one and a half times as long as the coxa, of somewhat 

 less diameter, and bears near its end, outside, one or two small hairs. 

 The tibia is scarcely as long as the femur, but more slender and with 

 three or four hairs. The tarsus is about two-thirds as long as the tibia, 

 tapers toward the end, and is terminated by a curved claw swollen at 

 its base, and by four digitules. The two upper digitules are long and 

 slender, terminated by globular knobs at the end, and inserted near the 

 end of the tarsus on each side. The two lower digitules are shorter, 

 club-shaped, gradually enlarged from the base to the tips, are equal in size, 

 and appear to be inserted on the swollen base of the claw. The legs 

 when at rest are held nearly in the positions shown in fig. 26, the four 

 posterior legs resting in the sternal cavity. 



The abdomen occupies less than half of the entire length, but is con- 

 siderably more bulky than the cephalo-thorax. The first six segments, 

 as in the larva, are similar in form, but become progressively smaller 



* Signoret 8t,at,(;« that this same variation occurs in P. vit-es- EssaLsur leg Cocfienilles, 

 p. (222.) 



