§ 842. THE INSECTA. 435 
thin cutaneous membrane, and containing one or several finely-divided 
trachean trunks. These trachean branchiae are either isolated, or fasci- 
culated ; in this last case, they are often digitiform, or penniform, and their 
uitimate 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, Hphemeridae, Perlidae, Libellulidae, and 
with the Gyrinidae. 
This trachean system is most simple with the larvae of Tipulidae of the 
genera Chironomus, Tanypus, Corethra and Simulia, as also with some 
larvae of the Phryganidae, of the genera Rhyacophila and Hydropsyche, 
where the tracheae, instead of forming cutaneous appe~laces, are sub- 
cutaneous and can therefore extract air from the water. The ta:vae of Core- 
zhra 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 
Simulia, 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, the larvae and pupae of Agriow and Calo- 
1 See Réeaumur, Mém. loc. cit. V. Pl. VI. fig. 7, 
or Lyonet, Mém. du Mus. XIX. Pl. IX. fig. 14, 
15. 
28ee Verdat and Fries, in Thon’s Entom. 
Arch. II. p. 66, 69, Taf. III. One must be careful, 
and not confound, as has sometimes occurred, the 
hairy tufts of these larvae for the tufts of tracheae. 
8$ee Degeer, Abhandl. I. Abth. III. p. 85, 
Taf. XXXVII. fig. 5, 6. 
4 See Roesed, Insektenbelust. II. Insecta aquat. 
Class. II. Taf. XXIII; Degeer, Abhandl. II. 
Taf. XXIIL; Suckow, in Heusinger’s Zeitsch. 
II. Taf. ILI. tig. 238, 24; and Pictet, Ann. d. Sc. 
Wat. ¥. 1836, Pl. III. During the passage into 
the pupa state, which occurs with Sia/is out of the 
avater, these tracheae are cast off. 
5 See the figures of Pictet, Recherch. pour servir 
a Vhist. et & Vanat. d. Phryganides, Pl. II. &c., 
and Degeer, Abhardl. [I. Taf. XII. The bran- 
chiae are ramose with Hydropsyche, and Rhya- 
cophila. 
6 See Swammerdamm, Bib. der Nat. Taf. XII1.~ 
XV.; Réaumur, Mém. VI. Pl. XLIL-XLVI.; De- 
geer, Abhandl. II. Taf. XVL-XVIIL.; Surkow, 
in Heusinger’s Zeitsch. II. Taf. III. fig. 21, 225 
Carus, Entdeck. eines Blutkreisl. loc. cit. Taf. III.; 
and the figures of Pictet, Hist. d. Insect. Névropt. 
Ephémérines. 
7 See the figures of Pictet, Hist. d. Névropt., 
Perlides. According to Newport (Ann. of Nat. 
Hist. XIII. p. 21, or Froriep’s neue Notiz. XXX. 
p. 179, or Aun..d. Sc. Nat. I. 1844, p. 183), 
these branchial tufts persist, with Pteronareys 
regalis, to the imigo state. This would be a 
very extraordimary anomaly, and should be coa- 
firmed, for, from the observations of Newport, it 
does not appear that the tufts of hair situated on 
the thorax of this Perlide really preserve the struc 
ture of branchial tufts. 
