INTERNAL ANATOMY OF INSECTS. 159 



A. viridtssima this organ is straight, in A. verrucivora 

 bent like a sabre, and in Pteropliylla citrifolia and some 

 others, the whole machine is short and boat-shaped ; in 

 Scaphura Vigorsii it is also rough with sharp little tuber- 

 cles a . I had an opportunity of observing, with respect 

 to the first of these insects, that in boring, as is the case 

 with the Cicada and saw-flies, the motion of the valves 

 was alternately backwards and forwards. It appeared 

 also to me that the two outer pieces of each of the ap- 

 parent valves were fixed in a groove in the margin of 

 the intermediate one. I saw this clearly with respect to 

 the upper pieces, and it is most probable that the lower 

 are similarly circumstanced. In the cricket tribe (Gryllus) 

 the ovipositor is as long as the abdomen, very slender, 

 terminating in a knob b . It is apparently bivalve like 

 that of Acrida, but I believe is resolvable into the same 

 number of pieces. 



In the Homopterous Hemiptcra there seems to be more 

 than one type on which the ovipositor is constructed. In 

 an insect very common with us, the froth froghopper 

 (Cercopis spumaria), some approach is made to the ovi- 

 positors last described, at least the number of pieces is 

 the same for it has a pair of external valves forming a 

 sheath, which includes three sharp lamina resembling 

 the blades of a lancet, the middle one of which can be se- 

 parated into two ; this instrument De Geer had reason 

 to think was scored transversely like a file c . In the in- 

 sects of this Order so noted for their song d (Cicada), 

 there are only Jive pieces ; namely, two valves forming the 



* This insect, which connects Conocepkalus, Acrida, &c. with Lo- 

 custa, is also distinguished by antenna; at first filiform and then 

 setaceous. h Dd Geer iii. t. xxiv./. 1, 12. 



c Ibid. 170. /. xi./. 19. < VOL. II, p. 397. 



