154? STATES OF INSECTS. 



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 a . Jointed anal organs are observ- 

 able in other larvae : those in that of a saw-fly described 

 by De Geer (Lyda F.) consist of three joints 5 ; in that 

 of Hister cadaverinus, a carnivorous beetle, of two c . 

 The larva as well as the pupa and imago of Ephemera 

 is furnished with three long diverging multiarticulate 

 tails, which are probably useful as a kind of rudder to 

 assist and direct their motions. That of the smaller 

 dragon flies (Agrion F.) is furnished with three long ver- 

 tical laminae, by moving which, as fish do their tails, 

 from side to side, the animal makes its way in the water d . 

 That singular one, also, with a hooked head, figured by 

 Reaumur, has a single swimming lamina, or fin, shaped 

 like a fan, and placed in a vertical position under the 

 tail e . 



The whole circumference of the body in some coleopte- 

 rous larvae, — for instance, in that of the tortoise-beetle 

 lately mentioned, — is surrounded with appendages like 

 rays. These are sometimes simple, rough with very 

 short spinous points f ; but I have a dipterous larva, in 



a Reaum. v. 32. t. v./. 3—5. Latr. Gen. Crust, et Ins. iv. 249. 



b De Geer ii. 1031. t. xlf. 13, 14. kk. 



c JV. Diet. eTHist. Nat.x. 430. 



d De Geer ii. 697. t. xxi./. 4, 5. b b b. 



e Reaum. v. t. vi.f. 7. n. 



1 Plate XVIII. Fig. 2. 



