FKMALE ORGANS OF GENKRATION. 199 



margin beset with short serrated teeth (f. 9 and 10). That the bee's 

 sting is similarly formed, although it lies in the abdomen, is shown in 

 Swammerdamm's figure *. Latreille cites the true aculeus in Sirex 

 as doublet, but personal investigation will readily con/ince of his 

 error and the correctness of our representation. The spirally twisted 

 aculeus of Cynips (PI. XXIII. f. 15 18), according to the opinion of 

 early entomologists, viz. of Roesel, differs in structure from that of the 

 bee's only in that its apex, which is covered by valves beset with hair, 

 projects above the abdomen. Its supposed spiral twisting consists in 

 its base being somewhat bent ; the point however somewhat sinks, so 

 that it represents the figure of an S. (f. 16. a section ; a, , the valves ; 

 b, b, the two exterior setae lying in it ; c, the central one). 



The description of the aculeus of the Cicada still remains. Its form 

 in C. Fraxini is as follows : the large triangular dorsal plate of the last 

 abdominal segment (PI. XXIV. f. J.A.), which at its apex is bent 

 down, covers from above the two double-jointed sheaths (the same, B. 

 and c.). Both joints are connected together by a soft membrane ; the 

 basal joint (f. 2. B. B ) is broader, shorter, and hollowed out ; the last 

 joint (the same, c. c.) is longer, narrower, towards its apex somewhat 

 broader, triangular, within hollowed in a channel. This last joint is 

 free, but the first is connected by a joint to the ventral plate. Between 

 these lie the aculeus (the same, D.), a horny, round organ, a little 

 dilated at its base, and near its apex compressed, where at the edge it 

 is toothed ; and this again consists of three horny ridges connected by 

 soft membrane. A still larger one (f. 3, , a, seen from beneath, f. 5 

 from above), broader in front, and there likewise toothed at the margin, 

 lies above and forms the channel ; two finer narrower ones, pointed at 

 the apex (f. 3, b., b, from beneath, and f. 4 from above) lie in the pre- 

 ceding, and project beyond it at the end, forming its apex (the same, 

 f. 2 D.). They all form combined a tube capable of distension, in which 

 doubtlessly the eggs are pushed down by the valves themselves after 

 the aculeus has pierced the vegetable substance, for which purpose 

 evidently it is armed at its apex with the strong teeth. 



This, therefore, is the structure of the ovipositor in the different 

 groups of insects : in its investigation we have concluded our exami- 

 nation of the female sexual organs, and pass now on to the male organs. 



* Bihlia Nsiturae, PI. XVIII. f. 3. f Gen. Cms. et Ins., vol. iii. p. 242. 



