COMPOSITION OF THE OVIPOSITOR. 



15 



complete pupa of the Humble-bee, and other thin-skinned 

 ll\ menopterous larvae, and in a less satisfactory way in the 

 young Dragon-flies. 



If the larva of the Humble-bee be taken just after it hag 

 become full-fed, and as it is about to enter upon the pupa state, 



the elements 



a a 



< --)*O (sterna - rhab- 

 dites Lacaze- 

 Duthiers), or 

 tubercles, 

 destined to Fig. 10. 

 form the ovipositor, lie in 

 separate pairs, in two groups, 

 Fig. 14. Fig. is. exposed distinctly to view, 



as in Figures 14-18. The ovipositor thus consists of three 



pairs of slender non-articulated tubercles, situated in juxta- 

 position on each side of 



the mesial line of the 



body. The first pair arises 



from the eighth abdominal 



ring, and the second and 



third pair grow out from 



the ninth ring. The ends 



of the first pair scarcely 



reach beyond the base of 



the third pair. With the 



growth of the semi-pupa, 



the end of the abdomen 



decreases in size, and is 



n a. 



Fig. 18. 



18 a. 



FIG. 14. Rudiments of the sting, or ovipositor, of the Humble-bee. 8, 9, 10, 

 sternites of eighth, ninth, and tenth abdominal rings in the larva. , first pair, situ- 

 ated on the eighth sternite ; b, second and inner pair ; and c, the outer pair. The let- 

 tering is the same in figures 14-22. The inner pair (6), forms the true ovipositor, 

 through which the eggs are supposed to pass when laid by the insect, the two 

 outer pairs, a and c, sheathing the inner pair. Ganin shows that in the embryo 01' 

 Poly nema (Fig. 055), the three pairs of tubercles arise from the 7th, 8th and 9th s?g- 

 ments respectively. FIG. 15, 10. The same a little farther advanced. 



FIG. 17. The three pairs now appear as if together growing from the base of the 

 ninth segment ; 17 a, side view of the same, showing the end of the abdomen grow- 

 ing smaller through the diminution in size of the under side of the body. 



FIG. 18. The three pairs of rhabdites now nearly equal in size, and nearly 

 ready to unite and form a tube; 18n, side view of the same; the end of the abdo- 

 men still more pointed ; the ovipositor is situated between the seventh and tenth 

 rings, and is partially retracted within the body. 



