KITE-FLYING 



289 



with the lower part better developed than the upper, and this 

 is an adaptation to the habit of frequently leaving the water. 

 For this particular shape of tail gives the body a bias upwards, 

 and unless this is corrected by means of the pectoral fins the 

 fish rises obliquely to the surface, thence passing into the air 

 when the swimming movements are vigorous. As we have seen 

 (p. 41), the tail of a Shark is also unsymmetrical, with the upper 

 lobe better developed, thus facilitating progress downwards, while 

 the symmetrical tail of an ordinary bony fish, such as a Herring, 

 favours swimming directly forwards. 



SPIDERS (ARANEID^) AS PARACHUTISTS. The Australian Fly- 

 ing-Spider (Attus volans, fig. 827), a hunting form, possesses para- 



Fig. 827. Australian Flying-Spider (A this volans), showing the triangular parachute-flap on either 



side of the abdomen 



chute organs having a similar use to the enlarged pectoral fins 

 of a Flying-Fish. Either side of the abdominal region is provided 

 with a flap, and when the spider launches itself into the air these 

 flaps are spread out, presumably increasing the length of the leap, 

 and diminishing shock when the ground is once more reached. 



KITE-FLYING 



We have seen that the wings of flying birds may be passively 

 used as parachutes (p. 286), and they also serve as kites by which 

 their owners are borne aloft without effort, under certain con- 

 ditions to be spoken of more fully in the section Flight. Much 

 the same thing is true of Flying- Insects, Fly ing- Fishes, and the 

 Australian Flying- Spider. 



A more remarkable case is presented by the larva of a two- 



