DESCKIPTION OF PARTS. H 



elongated very lio.jiieiitl} heyoiul tlie I><xly. This is tlie eharacteristic of llic order Ortho- 

 ptera of systematic wTiteis ; and in this order, the wing grows with the body of the insect. 

 There is another modification of tlie anterior wing which seems to arise from an arrest of 

 development, as the organ ac(]iiire9 scarcely half its usual length : this modification has 

 served to establisli the order llvmiptcni of authors. 



A still more I)eautifiil modification of the wing of the insect is f >iuid in Imtterflies and 

 moths. In these the nifml>rane and network, constituting the frame and foundation- Work 

 of the organ, are covered with a mealy sul>stance,or what appears to the unassisted eye as 

 such. This substance, however, is a scale of a heautiflil workmanship, of a variable form 

 and size In different insects, and in different parts of the wing of the same insect : they 

 are beautiful objects for the microscope. Rude handling immediately destroys the beauty 

 of the wing, by detaching these scales, and leaving the membrane beneath naked and 

 broken. 



The wing, anatomically considered, is composed of two parts : the nrrrurcs, and 7ncm- 

 brane. The lormer are likened unto ribs, which start from the anterit)r angle, and branch 

 in various ways as they pass to the posterior margin. They give strength to the organ, and 

 serve an important purpose in supporting and staying the outstretched membrane. The 

 nervures are not, as might at first be supposed, solid ribs : they are traversed internally by 

 a spiral vessel and nerve. The membrane is double, although extremely delicate : this 

 delicacy, however, is no obstacle to the growth of appendages, such as hairs, etc., inasmuch 

 as it is frequently densely covered with them. The wing, divided by the branchinf and 

 anastomosing of the nervures, forms a network more or less fine. The spaces enclosed by 

 the branches are called cells or areolefs; and being quite constant in form and place, they 

 are employed in the determination of groups. Three areas are particularly noticed, namely 

 the costal, infennediafc, and anal areas. The wing has a base, and anterior and posterior 

 mai-gins : the first is the part attached to the sternum.; the two others define themselves. 

 The apex of the wing is the part opposite to the base. 



Various views have been expressed by different authors on the analogical relations of the 

 wings, many of which are certainly very fanciful. M. Aidovin takes a rational common 

 sense view of these relations, and regards the winir^ as organs sui gaieris, intended for the 

 exercise of special functions. 



The lkgs. Each segment of the thorax supiH^rts a pair of legs. The joint which unites 

 them with the boily is called the coxa or hip : it is held in its socket by a ligament. The 

 motions of the leg are controlled more or less by the form of the coxa. The thigh is the 

 largest portion of the leg : its form is various ; it is cylindrical or flattened, it is straight 

 or arched. If the insect leaps, the {wsterior thighs are thick and strong. The lees are also 

 more or less sjiinous. 

 The tibia is the next part of the leg, and fanis an angle with the thigh. It is more 



