AQUATIC LARV^. 311 



employ in their progression through the water. 

 Another use is also made of these tufts of hair ; 

 for by repelling the water, they allow of the 

 insect's suspending itself from the surface of the 

 fluid in the manner already noticed in giving 

 the history of the evolutions of the hydra.* 



The impulse given by the lateral inflexions of 

 the body are in many cases assisted by short 

 legs ; but the larvae of the Ephemera^ though 

 furnished with legs, do not use them for this pur- 

 pose, and swim simply by the action of the tail . 

 Those of the Dytiscus are furnished with a pair 

 of very long members, projecting to a consider- 

 able distance from the sides, and flattened at the 

 ends, to serve as oars. The larvae of the Hydro- 

 philus are also admirably formed for swimming ; 

 and they not only dart forwards with surprising 

 velocity, but also turn in all directions with the 

 utmost facility. 



§ 5. Terrestrial harvce. 



The movements of larvae that are not aquatic 

 are perfectly analogous to those of the Annelida, 

 which they much resemble in their outward 

 form and mechanical structure. The muscles 

 by which the annular segments of the body are 

 moved, are exceedingly numerous, and beauti- 

 * Page 179. 



