ORTHOPTERA. 555 



organisation. The head usually bears long, multiarticulate antennae, 

 facetted eyes of considerable size, and also simple eyes. The oral ap- 

 paratus is adapted for masticating and biting. On the under-lip 

 (Idbium) the four lobes, and sometimes also their supports (stipites), 

 remain separate from one another. The prothorax, the size of which 

 is very variable, is always freely moveable, and separated from the 

 mesothorax by an articulation. The form and structure of the 

 wings is extraordinarily variable. The anterior wings frequently 

 have the form of coriaceous wing covers, or, at any rate, are 

 stronger and thicker than the larger posterior wings, which can 

 be folded together. In other cases, both pairs of wings are similarly 

 formed and have a net-like appearance, like those of the Neuroptera. 

 The legs also vary in their form, the tarsus consisting rarely of two, 

 usually of three, four or five joints. 



The abdomen usually preserves the full number of segments, and 

 ends with caudal appendages having the form of pincers, stylets, 

 filaments or setae ; ten segments usually take part in its construc- 

 tion, the genital opening being on the ninth, and the anus on the 

 tenth. On the abdomen of the female there is sometimes an 

 ovipositor (Saltatoria). This springs from the penultimate and 

 antepenultimate segment, and consists on either side of an upper 

 and a lower valve, and an inner spinous rod lying on the upper 

 valve and passing along a groove on the upper edge of the lower 

 valve. 



Many OrtJioptera have a dilatation of the oesophagus which may 

 be called a crop, and a gizzard ; this is followed by the chylific 

 ventricle, which often has some csecal appendages at its anterior 

 end. The salivary glands are often extraordinarily large, and are 

 provided with a vesicular reservoir. The number of the Malpighian 

 vessels is, with a few exceptions, very considerable. The ventral 

 ganglionic cord presents three larger thoracic ganglia, and five, six, 

 or seven smaller abdominal ganglia. Some Ortkoptera possess tym- 

 panic auditory organs. The generative organs consist, as a rule, of 

 numerous egg tubes and testicular sacs. Large glands open into 

 their efferent ducts. A bursa copulatrix is absent. 



All OrtJioptera undergo an incomplete metamorphosis. The two 

 sexes are distinguished, not only by the differences of the external 

 copulatory organs and by the size of the abdomen, but sometimes by 

 the size of the wings (Perijilaneta), or by the absence of the wings 

 in the female (fleterogamia, Pneumora) ; and in the jumping Orthop- 

 tera (Saltatoria) by the development of a voice organ on the body of 



