IN8ECTA. 429 



the feet. The metamorphosis is incomplete, with only few excep- 

 tions (the males of the gall-insects and the genus Aleurodes). 



With respect to the natural affinity of this order, and its place in 

 a natural arrangement of insects, we remark that it agrees with 

 the Ortkoptera in the imperfect metamorphosis, but differs from this 

 order very greatly in the oral organs and in the internal structure. 

 The last family of the preceding order, the Perlce and Termites, on 

 the contrary, have a position very close to the Orthoptera ; and it is 

 only with reluctance that we interrupt this natural transition by 

 interposing the Hemiptera between them. But the Hemiptera, 

 whatever position be allotted them, must always stand by them- 

 selves as a very deviating group of insects. The absence of 

 maxillary palps might perhaps be considered to be their most 

 important character, which elsewhere in the class of insects are 

 more constant in their presence than the labial palps 1 . Some 

 species of Hemiptera homoptera (the genus Plata) have some 

 resemblance to the Lepidoptera, which however, is rather an 

 external similarity (analogy) than a true relationship (affinity), 



The intestinal canal of the hemiptera is long, (see above, p. 253). 

 In many CicadaricB (Cicada, Ledra, Cercopis, &c.) there is an 

 arrangement, which was formerly considered to be a return of the 

 intestine into the stomach, but which has been since described by 

 DOYERE in a more satisfactory manner; the tortuous intestinal 

 canal does turn back to the stomach and attaches itself to it, to 

 leave it subsequently at another point ; but it does not open into 

 the stomach, but merely runs along its wall, between the coats of 

 the organ 2 . In some Geocorisce (Scutellera, Pentatoma, and some 

 species of Coreus) the inferior part of the stomach before the 

 insertion of the vasa urinaria is tortuous, and consists of four 

 (in Coreus marginatus of two) grooves or semi-canals, which have 

 transverse white rings or folds of even width, between which there 

 is a very thin and transparent membrane 3 . Salivary glands are 

 ordinarily much developed; mostly more than one pair are pre- 

 sent; they are situated on each side of the intestinal canal, arid 

 open into the oesophagus ; in the leaf-lice they appear to be wanting. 



1 RATZEBURG indeed describes in Cicada a three-jointed maxillary palp (Mediz. 

 \Zool. ii. Tab. 27, figs. 16, 17); but this part, according to BURMEISTEB, is a jointed 

 horny process, to which muscles are attached. 



2 Ann. dcs Sc. not. ie SeVie. Tome xi. 1839, PP- 81 85. PI. I. 



3 RAMDOHR has given to this part the name of Wanzenmagen. 



