394. PHYSIOLOGY OF THE INVERTEBRATA. 



in the act of flying, as is the case with the Lepidoptera, Hymen- 

 optera, the majority of the Newroptera, the lAhelludidce, Perlidce, 

 and finally, the Oicadidce, and the Aphididce. The muscles 

 of the anterior wings are comparatively smaller than those of 

 the posterior, when the first are not used, properly speaking, 

 except to cover the latter, as is the case with the Coleoptera, 

 the Bugs, andmany of the Orfhopfera." (Von Siebold.) 



There are also certain accessory organs which aid in the 

 phenomenon of fiight. Prof. Huxley says that " the air-sacs 

 doubtless assist fiight by the diminution of the specific gravity 

 of the insect, which follows upon their distention." 



Concerning the phenomenon of flight Sir Richard Owen 

 has justly remarked that " in no part of the animal kingdom 

 is the mechanism for flight so perfect, so apt to that end, as 

 in the class of insects. The swallow cannot match the dragon- 

 fly in its aerial course ; this insect has been seen to outstrip 

 and elude its swift pursuer of the feathered class : nay, it can 

 do more in the air than any bird — it can fly backwards and 

 sidelong, to right or left, as well as forwards and alter its 

 course on the instant without turning." * 



The Aeachnida. 



In the Arachnida the organs of locomotion are all fixed to 

 the cephalo-thorax, and consist of eight pairs of limbs, strongly 

 resembling those of the Jjisecta ; and alcaost always termiaated 

 by two iooks. The length of these organs is generally con- 

 siderable, and they easily break ; but, as in the Crustacea, the 

 stump, after having cicatrised, reproduces a new limb, which 

 increases by little and little, and ends by becoming similar to 

 that of which the animal had been deprived. 



* The flight of the bee exceeds twelve miles an hour, and It will go four 

 miles in search of food. Its wings, braced together in flight by a row of 

 hooklets, bear it forward and backward, upward, downward, or suddenly 

 arrested course, by a beautiful mechanical adaptation. (See Cowan's ^nei; 

 Bee.) For a full exposition of the flight of insects the reader is referred 

 to the work of Ch3.briejr in Mim. du MvsSam, tomes 6-8 



