222 THE MECHANICAL FUNCTIONS. 



§ 5» Terrestrial Larvae.. 



The movements of larvse that are not aquatic are perfectly 

 analogous to those of the Annelida, which they much resem- 

 ble in their outward form and mechanical structure. The 

 muscles by which the annular segments of the body are 

 moved, are exceedingly numerous, and beautifully arranged 

 with reference to the motions they are intended to effect. 

 The investigation of the structure of these minute organs 

 has Ions exercised the talents of the most skilful entomo- 

 logists, and still offers much that remains to be explored. 

 The researches of Lyonet, already alluded to, on the anato- 

 my of the larva of the Bomhyx Cossus,^ of which he has 

 published an elaborate description, accompanied by admi- 

 rable engravings, will ever remain a splendid monument of 

 patience and ingenuity in overcoming the difficulties which 

 impede this kind of inquiry. la the body and the limbs of 

 this caterpillar, Lyonet counted above 4000 separate muscu- 

 lar bands, all arranged with the most perfect symmetry, and 

 adapted, with wonderful precision, to the performance of the 

 required effects. 



In these larvse, as in the simpler forms of the Annelida, 

 progression is often accomplished solely by the alternate 

 contraction and extension of the annular segment, aided in 

 many cases, by short hairs, and frequently, also, by a slimy 

 secretion which exudes from their bodies. Many larvae, 

 which are destitute of feet, move onwards by first coiling 

 the body into a circle, making the head and the tail meet, and 

 then springing forwards by a sudden extension of the back, 

 producing an effect like the unbending of a bow. By an 

 artifice of the same kind, some larvse contrive to leap to a 

 considerable distance, by the violent efforts which they make 

 in unfolding the curvatures of their bodies. 



Some larvss avail themselves of their jaws in order to fix 

 the head, and drag the rest of the body towards it. In this 

 manner do the larvse of the Capricorn beetles advance along 



• C0SSU6 ligniperda. Fabricius. 



