4-'28 EXTERNAL ANATOMY OF INSECTS. 



large, triangular, and shaped like the head of a hatchet- 1 ; 

 and at others it resembles the moon in her first quar- 

 ter 5 . In the great dragon-fly, or demoiselle if you pre- 

 fer the gentler French name {JEshna F.) the labial palpi, 

 which are without any visible joints, are terminated by a 

 minute mucro or point c . With regard to their direction 

 and flexure, they frequently, as in the instance just men- 

 tioned, turn towards each other, and lie horizontally upon 

 the end of the labium. Sometimes, as in the Cicindelidte, 

 they appear to point towards the tail of the insect, the last 

 joint rising, and forming an angle with the rest of the 

 feeler. In other instances they diverge laterally from the 

 labium, the last joint turning again towards it at a very 

 obtuse angle. 



4. Mandibulce d . — Having considered the analogues of 

 the lips in our little beings, I must next call your atten- 

 tion to the representatives of the jaws. The vertebrate 

 animals, you know, are mostly furnished with a single 

 pair of jaws, one above and the other below, in which the 

 teeth are planted and which have a vertical motion. But 

 insects are furnished with two pair of jaws, a pair of 

 upper-jaws and a pair of under-jaws, which have no 

 teeth planted in them, and the motion of which is hori- 

 zontal. — I shall begin with an account of the upper-jaws. 

 These by modern Entomologists, after Fabricius, are de- 



a Plate XIII. Fig. 2. Linn. Trans, xii. t. xxi./. 6. b. 



b This is the case with Oxyporus F. Plate XIII. Fig. 4. 



c Plate VI. Fig. 12. b". Latreille, N. Diet. d'Hist. Nat. xvii. 

 545, seems not to regard these as palpi; but from their tubular form, 

 and insertion in the socket of the labium, it is clear that they ought 

 to be so considered. <J Plates VI. VII. XXVI. c'. 



