The Grasshopper 



337 



tutes a collar which is drawn out into a shield above. The wings, as 

 already stated, are attached to the dorsal side of the mesothorax and 

 metathorax. 



The wings are divided by veins or nervures (Fig. 218) into so-called 

 cells. Although these veins, or nervures, vary considerably in different 

 species, they are quite constant in members of the same species and so 

 are often used as a basis of classification. 



The principal longitudinal veins are the costa ( ), 



subcosta, radius, media, cubitus ( ), and anal. 



There are also cross veins. Any variations are the result of either 

 additional and lessened number of those just mentioned. In beetles the 



fore-wings are sheath-like and called elytra ( 



The fore-wings of grasshoppers and all members 



grouping are leathery and called tegmina ( 



The abdomen consists of eleven segments, the 

 clearly defined than the others. 



The entire exoskeleton is divided by sutures ( 

 into distinct pieces, the sclerites ( 

 of these sclerites may fuse. 



)• 



of the Orthoptera 



)• 



posterior one less 



) 



), though several 



Fig. 219. Ear of Locust (Caloptenus italicus) as seen from the inner side. 



T, tympanum; TR, its border; o, it, two bone-like processes; bi, pear-shaped 

 vesicle; n, auditory nerve; ga, terminal ganglion; st, stigma, or spiracle; m, open- 

 ing muscle, and m 1 closing muscle of same; M, tensor muscle of tympanic mem- 

 brane. (After Graber.) 



The sclerites (Fig. 204, A) on the dorsal surface are called tergites 

 ( ). These are often fused together in various 



insects. The sclerites on the ventral surface are known as sternites 

 ( ), while the side walls connecting dorsal and 



ventral sclerites are called pleurites ( ). 



