388 EXTERNAL’ ANATOMY OF INSECTS. 
Breathing-pores observable in some genera in the 
intermediate ventral segments, one on each side 7.— 
Ex. Dynastes Aloeus, &c. 
4, Exastes (the Elastes). The elastic organs on the 
ventral segments of Machilis polypoda which assist 
this insect in leaping. 
iii, Petroxus (the Footstalk). A slender part by which 
the abdomen of many Hymenoptera is united to 
the trunk, in some genera very long, in others very 
short, and in others wanting. It includes the Fw- 
niculus, Foramen, Squama, and Nodus. 
1, Funicutus (the Funiculus). A small cartilaginous 
cord, passing through a minute orifice of the Post- 
frenum, just above the point where the footstalk is . 
fixed, to an opposite hole above it, which enables the 
animal the better to elevate or drop the abdomen «. 
2. ForaMEN (the Foramen). The orifice in the abdo- 
men, through which the above cord passes’. 
3. Squama (the Scale). A vertical flat scale, observable 
on the footstalk of the genus Formica, &c.° 
4. Nopt (the Knots). One or more subrotund protube- 
rances of the footstalk in the genus Myrmica ‘. 
iv. Caupa (the Zaz/). Where the abdomen grows sud- 
denly slenderer, and terminates in a long jointed 
tail, as in Scorpio and Panorpa’. It includes the 
Centris. 
1. Cenrris (the Centris). - The last inflated joint of the 
tail, terminating in the Sting. 
* Prave VIII. Fic. 9. DI. > Prats IX. Fre. 17, 18. C. 
© Ibid. Fic. 13. F’. 4 Ibid. G’. 
e Ibid. Fic. 17. H. f Ibid. Fre. 18. J’. 
& Pirate XV. Fre. 12. D, 
