STATES OF INSECTS. (Larva.) 153 
parallel to the back, with its points towards the head, the 
anal aperture points the same way. When the animal 
walks, the fork points the other way, and is in the same 
line with the body, and the anus assumes a prone posi- 
tion ?. 
The larve of a genus of flies (Volucella) remark- 
able for inhabiting the nests of humble-bees, are di- 
stinguished on their upper side by six long, diverging, 
pointed, membranous radii; placed in a semicircle round 
the anus’: what the particular use of these organs may 
be, has not been conjectured. Another in my collection 
has only four upper radii, but below the anus are two 
fleshy filiform tentacula. One of a Tipularian described 
by Reaumur, has also four upper teeth; but instead of 
two subanal tentacula, has six*. The singular larva of 
another of this tribe (Chironomus plumosus) has on the 
two last segments four, long, fleshy, filiform, flexible ten- 
tacula, often interlaced with each other; which, accord- 
ing to the same illustrious author, are used by the ani- 
mal to fix its caudal extremity, like the geometers, that the 
. other end may be at liberty. Besides these organs round 
the anus, it has also four other oval ones, of uncertain 
use: not to mention the two prolegs, which M. Latreille 
thinks are air-tubes*. Jointed anal organs are observ- 
able in other larvze: those in that of a saw-fly described 
by De Geer (Zyda) consist of three joints °; in that of 
Hister cadaverinus, a carnivorous beetle, of two. The 
* De Geer v. 170—#. v. f. 19—23. Compare Reaum. iii. 235—. 
_> Prare XIX. Fic. 11. a. De Geer vi. 137. Reaum. iv. 482, 
© Reaum. iv. ¢. xiv. f. 9, 10. 
: Reaum. v. 32. ¢. v. f. 3—5. Latr. Gen. Crust. et Ins. iv. 249. 
f 
De Geer ii. 103]. ¢. xl. f. 13, 14. & A. 
N. Dict. d’? Hist. Nat. x. 430. 
