CENTIPEDES. 155 



M. Veiss, quoted by Griffith, the Scolopendra forcipata (belonging 

 to Dr. Leach's genus Lithobius), when walking, successively moves 

 its numerous legs, one portion of which are brought in contact with 

 the line of position, whilst the others are raised up ; the latter 

 are quickly put down to the ground, whilst the posterior pair of 

 each division (comprising two segments*) is raised. All these 

 various movements, which follow along the body from the head to 

 the hinder extremity, produce an undulated motion. The insect 

 varies its movements and their degree of force, according to ne- 

 cessity, each foot resting on the line in which it walks, and trans- 

 porting the body in the same way as do the muscles of the snail, 

 to the distance in which the limb can act. These iusects are also 



a, Lithobus forcipatus ; 4, Geophilus longicornia. 



able to run backwards with much agility, at which time they how- 

 ever make use only of the two hind pairs of legs, which, when 

 walking forward, are dragged motionless after the body. 



These animals have been considered to be universally carnivo- 

 rous ; but from the situations in which I have repeatedly found 

 some of the English species, I should be disposed to assign them, 

 at least in some degree, an appetite for decaying vegetable matter. 

 Dr. Leach has also given the name of Geophilus carpophagus to 

 one of the species, from its feeding upon fruit. One of the British 

 species, the electric centipede (Scolopendra electrica Linn.), pos- 

 sesses the remarkable property of emitting a phosphorescent light 



* The segments of the bodies of insects have generally two spiracles. 

 If the bodies of the centipedes, especially those of the large exotic spe- 

 cies, be regarded in this point of view, in which there are twenty-one pairs 

 of legs, it will be observed, that the spiracles are placed upon alternate 

 segments, whence, in comparison with the structure of the true insects, 

 these segments must be considered as representing only semi-segments, 

 from whence it is evident that each entire segment is provided with two 

 pairs of legs, but with only one pair of breathing holes, one pair of the 

 former organs, at the tail, being supernumerary. Mr. MacLeay has 

 followed up this theory of M. Latreille, in his memoir upon the thorax of 

 insects, published in the Zoological Journal. 



