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Fig. 187.—1, abdomen of Cynips, showing the great dorsal segment, the peduncle, and the position of the ovipositor within; 2, the entire ovipositor; a, lateral scale; a′, its valve; b, anal scale; b′, stylet; c, support of the stylet; e, base or support of sting (fi); 3, profile showing the relation of the genital armature to the rest of the abdomen, the 6th sternite having been drawn to show its full size; 4, anal scale (b) and stylet; e, i, supports and body of the stylet; c, piece uniting the two scales; 5, lateral scale (a), and a′ sheath; d, support of the sting (f); 6, transverse section of the body through the sting (diagrammatic); R, internal armature; o, oviduct; a, lateral scale; a′ its valve; e, support of the stylets (i); b, anal scale; c, piece uniting two scales; f, sting; d, its support; 7, a second section simpler and more theoretical than the first; 8, diagrammatic, all the elements of the sting have been reduced to pieces of the same form.—After Lacaze-Duthiers.

An objection to this view is the fact that the posterior pairs of styles appear to arise both from one and the same segment,—the ninth. Dewitz questions whether the four appendages of the ninth segment represent two pairs of limbs, or one pair split into two branches, and prefers the latter view, but leaves it as a point to be settled by future investigations. As will be seen below, both Kraepelin and Bugnion observed a pair of rudiments to each of the three penultimate segments, those of the middle pair splitting in two. Wheeler maintains, erroneously we think, that the inner of the two pairs on the ninth segment represents the tenth pair of abdominal appendages; but in reality this latter pair become the cercopods. That there are probably originally in insects of all the orders provided with an ovipositor three distinct pairs of appendages, one to each segment, is proved, or at least strongly suggested, by Ganin’s researches on the three pairs of abdominal imaginal discs of the third larva of Platygaster and Polynema (Fig. 188), which are transformed into the ovipositor. He remarks that these imaginal discs have the same origin and pass through the same changes as those in front, i.e. those destined to form the thoracic legs. Dewitz has shown that the germs of the ovipositor of the honey-bee arise as buds on the two segments before the last (Fig. 189).