442- THE INSECTA. § 346. 



of the Geocorisae.® With some species, their excretory ducts form one or 

 two vesicular dihitations situated above the colon.**' It is only with a few 

 Geoeorisae, and with the Cicadidae, that the extremities of these canals are 

 free.<^* With this last group, and with the Cercopidae, they creep with a 

 portion of the intestine, between the tunics of the ante-stomach, before 

 opening into the lower extremity of the true stomach.**" 



With the Diptera, there are four long uriuiferous vessels. The Culici- 

 dae and Psychodae, alone, by exception, have five.*^' With very many 

 species, these canals are united in twos, and open, by a common excretory 

 duct, into the lower extremity of the stomoch.'-' Loop-like anastomoses 

 occur only with the Tipulidae, Leptidae, and Bombylidae.'^' t 



With the Lepidoptera, there are nearly always six long, free, uriniferous 

 tubes, which open into the stomach by two excretory ducts.'"' 



The Hymenoptera are distinguished for their considerable number of 

 these vessels, which are usually short and surround the pylorus in numbers 

 of twenty to one hundred and fifty.*"' With the Orthoptera, these vessels 

 are inserted in a similar manner, *^-' but are often much more numerous. '^^* 

 The Tcrmitidae, alone, form an exception, — having only six.*"* 



The true Neuroptera are distinguished from the Orthoptera in that their 

 vessels of this nature are long, flexuous, and only six to eight in number.*^'" 



With the Coleoptera, they are usually long, make numerous convolutions, 

 and never exceed four or sis in number.*^"' When four, they are nearly 

 always joined by twos at their extremity ; and when six, they are often 

 attached by their extremities to the colon. *''^' 



The urinary vessels of the larvae and pupae resemble somewhat those of the 

 perfect Insecta.*^-' With the larvae of certain Hymenoptera, and Orthoptera, 



3 With the Naucoridae, Nepidae, with Salda, 12 With the Ephemeridae, alone, the form of 

 Capsiis and Reduvius. With Dorthesia, the these canals is somewhat different, in that their free 

 foiu- canals form also two short loops ; see L. Du- extremities are nearly always thickened, and that 

 four, Recherch. &c. p. 19, PI. I.-IX. the excretory ducts take one or two spiral turns. 



4 Pentntoma, Tetyra, Pyrr/iocoris, Lygaeus, I'! See L. Diifour, Recherch. sur les Orthopt. 

 Gerris, Stenocephalus. &c. PI. I.-IV. XI. XIII. Gryllotalpa is distin- 



5 Cimex, Ploiaria, Miris, Alydus and Coreus. guished from the other Orthoptera in that the 

 In the last two jrenera the uriniferous canals, free, urinary canals are disposed fasciculate and termi- 

 terminate at the pylorus in a common reservou'. nate in a single excretory duct. 



With Alydus, Aradas, Aneurus; Cixiux, Isfni.s, H L. Dufour, Recherch. loc. cit. PI. XIII. fig. 



and Asiraca, they unite in twos in a common ex- 196. 



cretory duct. AVith Psylla, they consist only of 15 L. Dufour, Ibid. PI. XI.-XIII. There are 



four rudimentary caeca; see L. Dufour, Recherch. six of these" vessels with the Phryganidae, Sialidae, 



loc. cit. Panorpidae, Rhapididae : and eight with the Myr- 



G It was a long time before there was an exact meleonidae and Heraerobidae. 

 idea of the canals with Cicada. Doycre (Ann. '6 There are four urinary vessels with the Cara- 

 d. Sc. Nat. XI. 1839, p. 81, PI. I.) was the first bidae, Staphylinidae, Gyrinidae, Palpicornes, Lii- 

 who perceived that they penetrated between the mellicornes, Cantharidae, and Buprestidae ; six 

 tunics of the stomach ; but he supposed they re- with the Byrrhidae, Nitidulidae, Dermestiilae, 

 appeared on its surface after a short course, lie Cleridae, Meloidae, Pyrochroidae, Bruchidae, Bos- 

 did not, therefore, attribute to these insects, only tricidae, Capricornes, Chrysomelidae, and Coccm- 

 two uriniferous vessels. This last error has been ellidae. 

 rectified by L. Dufour (Ibid. XII. p. 287). 1^ For the uriniferous canals of the Coleoptera, 



r See L. Dufour, Ann. d. Sc. Nat. XIX. loc. see, beside Ramdohr, and Suckow, loc. cit., L. 



cit. PI. VIII. fig. 2(i {AnopheUn). Dufour, Aim. d. Sc. Nat. 1824, II.-IV. ; 18^4, I. 



■S With the JIuscidae, Oestridae, Conopidae, PI. II. III.; 1S40, XIIl. PI. V. VI.; XIV. PI. XI.; 



Syrphidae, and Hippoljoscidae. With the Stratio- XIX. PI. VI. With Donacia, the six vessels 



raydae, the four canals unite into one excretory have a very peculiar aspect. Two pairs unite 



duct ; see Swammerdamm, Bib. der Nat. Taf. loop-like at their jiosterior extremities, and their 



XLI. fig. 6 (Stratiomus); L. Dufour, loc. cit. PI. anterior ends unite in a common reservoir ; while 



VIII. fig. 28 (Sargun). the third pair are free and open isolately at the 

 » Ramdohr, loc^' cit. Taf. XX. pylorus ; sue L. Dufour, Ann. d. Sc. Nat. 1824, 



10 With Pterophorus and Yponomeuta, Suckow IV. PI. VII. fig. 7, 8, and 1844, XIX. PI. VII. fig. 

 has found only four uriniferous vessels (loc. cit. Taf. 10. 



IX. fig. 159, 161). 1** Beside Ramdohr, and Suckow,\oc cit., see L. 



11 See L. Dufour, Recherch. sur les Orthopt. Dufour, Ann. d. Sc. Nat. XII. 1839, PI. I.; XIII. 

 PI. III.-X. The smallest number of these canals PI. V.; and XVIII. PI. IV. (larva of a Tipulide, a 

 is found with the Formicidae, Cynipidae, and Ich- Sapromyza, a Pyrochroa, and of a Cetonia, kc.) ; 

 neumonidae. De Haan, Nouv. Ann. du Mus. IV. PI. XVI.-XIX. 



