"§> 342. , THE INSECTA. 435 



thin cutaneous membrane, and containing one or several finely-divided 

 trachean trunk?. Tliese trachean brancliiae are either isolated, or fasci- 

 culated ; in this last case, they are often digitiform, or penniform, and their 

 ultimate ramifications are usually deficient in the spiral filament. All the 

 air-vessels which these branchiae contain, arise from the larger trachean 

 trunks. These branchiae occur with various Tipulidae, with a Nymphula, 

 with the Phryganidae, Sialidae, Ephemeridae, Perlidae, Libellulidae, and 

 with the Gyrinidae. 



This trachean system is most simple with the larvae of Tipulidae of the 

 genera Chironomus, Ta?iypus, Corethra and Simulia, as also with some 

 larvae of the Phryganidae, of the genera Rhyacophila and Hydropsycke, 

 where the tracheae, instead of forming cutaneous appendages, are sub- 

 cutaneous and can therefore extract air from the water. The larvae of Core- 

 thra are distinguished for having in the thorax and abdomen, directly 

 beneath the skin, two adjacent trachean vesicles, by means of which, very 

 probably, the necessary renewal of air takes place.*" With the pupae of 

 Simidia, there are two branchial tufts on the sides of the prothorax, com- 

 posed, each, of six to eight long caecal tubes, which contain each a single 

 simple trachea deficient in the spiral thread.'-' Of the various larvae of the 

 Lepidoptera, living under the water, that of Nymphula stratiotalis, alone, 

 has trachean branchiae. These consist of fasciculate filaments situated on 

 the sides of the abdominal segments.^'^' With the larvae of Sialis, each of 

 the six, seven or eight abdominal segments has upon its sides an articulated, 

 filiform thread, containing a trachean vessel, and which may, therefore, be 

 regarded as a trachean branchia.*^' Most of the larvae and pupae of the 

 Phryganidae, have, at the same points, one or two filiform, trachean 

 branchiae, rarely ramified, and united in groups of from two to five, which 

 stand out towards the back.'^' With those of the Ephemeridae, each of 

 the anterior abdominal segments has a pair of these branchiae which are 

 sometimes ramified in the most varied manner, and sometimes consist of 

 two kinds, some being lamelliform and alternating with the others which 

 are fasciculate. <"* With all the Ephemeridae, these organs have move- 

 ments which are sometimes slow and rhythmical, and sometimes rapid and 

 oscillatory. 



With the Perlidae, the branchiae are filiform, ramified, and situated on 

 the three thoracic segments of the larvae and pupae, or bound together in 

 several short fasciculi which cover the base of the legs.'"' 



Among the Libellulidae, jthe larvae and pupae of Agrio?i and Calo- 



1 See Reaumur, Mem. loc. cit. V. PI. VI. fi;;. 7, chiae are ramose with Hydropsycke, and Rhya- 

 or Lyonet, Mt-in. du Mus. XIX. PL IX. fig. 14, cophila. 



15. 6 See Swamnierdamm, Bib. der Nat. Taf. XIII.- 



2 See rerdat and Fries, in Thon's Entom. XV.; Reaumur, Uem. VI. PI. XLll.-XL\I.; De- 

 Arch. II. p. 66, 63, Taf. III. One must bo careful, ^eer, AblianiU. II. Taf. XVI.-XVIII.; Suckow, 

 and not conf')Uiid, as has sometimes occurred, the in He u singer's Zeitsch. II. Taf. III. fig. 21, 22 ; 

 hairy tufts of tliese larvae for tlie tufts of tracheae. Carus, Entdecli. eines Blutkreisl. loc. cit. Taf. III.; 



3 Sae De^eer, Abhandl. I. Abth. lU. p. 85, and the iinurcs of Pictet, Hist. d. Insect. N6vropt. 

 Taf. XX.XVII. fig. 5, 6. Ephemerines. 



4 See Roeael, liis;ktenbelust. II. Insecta acjuat. '' See the figures of Pictet, Hist. d. Nuvropt., 

 Class. II. Taf. XXIII.; Des:eer, Abhandl. II. Perlides. According to Newport (Ann. of Nat. 

 Taf. XXIII.; Suckow, in Heusinger'.i Zeitsch. Hist. XIII. p. 21, or Fror/fjtJ-s neue Notiz. X.KX. 

 n. Taf. III. tig. 23, 2-1 ; and Pictet, Ann. d. Sc. p. 179, or Ann. d. Sc. Nat. I. 1844, p. 18,3), 

 Nat. V. 1836, PI. III. During the passage into these branchial tufts persist, with Pteronarcys 

 the pupa state, which occurs with Sialis out of the regalis, to the imago slate. Tliis would he a 

 water, these tracheae are cast olT. very e.xtraordinary anomaly, an<l should be con- 



5 See the figures of Pj'c^e?, Recherch. pour servir firmed, for, from the observations of Newport, it 

 A I'hist. et k I'anat. d. Phrygauides, PI. II. &c.; does not appear that the tufts of hair situaterl on 

 and Deseer, Abhandl. II. Taf. XII. The bran- the thorax of ihis Perlido really preserve the struc- 

 ture of branchial tufts. 



