INSECTA. 429 
the fect. 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 Orthoptera 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 Perle 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'. Some 
species of Hemiptera homoptera (the genus lata) 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 Cicadarie (Cicada, Ledra, Cercopis, &e.) 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 
DoyeERE 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*. In some Geocorise (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*. Salivary glands are 
ordinarily much developed; mostly more than one pair are pre- 
sent; they are situated on each side of the intestinal canal, and 
open into the esophagus; in the leaf-lice they appear to be wanting. 
1? RaTzEBuRG indeed describes in Cicada a three-jointed maxillary palp (Mediz. 
Zool. 11. Tab. 27, figs. 16, 17); but this part, according to BURMBISTER, is a jointed 
horny process, to which muscles are attached. 
? Ann. des Sc. nat. 2e Série. Tome XI. 1839, pp. 81—85. Pl. 1. 
* RaMmDouR has given to this part the name of Wanzenmagen, 
