846 THE CRUSTACEA. $ 287. 
a condition to respire atmospheric air.? But with Tylos, this pulmonary 
apparatus is still more highly developed; for, under the four pairs of oper- 
cula, there are, instead of simple branchial plates, oblong appendages on 
which is a transverse row of aeriferous sacs having a kind of stigma on 
their under surface. 
All the Myriapoda respire by true tracheae. Their blood does not 
require, therefore, special organs to receive the influence of the air, for this 
last is carried into every part of the body. 
The stigmata for the ingress and egress of the air, are easily seen with 
the Chilopoda, for they are usually surrounded with a ring of brown chi- 
tine, and situated on each side of the body between the base of the feet 
and the dorsal shields; they are not found, however, above all the feet, 
for the segments which have them alternate more or less regularly with 
those that are without them.© With the Chilognatha, the very small 
stigmata are on the ventral surface. They are situated on the anterior 
border of the ventral plates, from the posterior border of which arise the 
feet. The intimate structure of these tracheae, which are usually brown, 
is exactly like that of those of insects. Among the Chilognatha, the 
Julidae are noticeable for the very simple character of their trachean 
apparatus. Hach stigma leads into a tuft of tracheae from which arise 
air-canals which neither ramify nor anastomose but gradually become 
smaller and smaller and surround the various organs. With the Glo- 
merina, on the contrary, the tracheae, which arise from the stigmata by 
two trunks,: are branched, but do not anastomose with the neighboring 
branches.” Those of the Chilopoda most closely resemble those of the 
Insecta, — being very ramose, and their large trunks intercommunicating 
at their origin by longitudinal and transverse anastomoses, so that each 
stigma can introduce air into the entire trachean system. 
1 According to Duvernoy and Lereboullet (loc. a.a.(Julus). These stigmata with Julus were 
He had re- 
cit. p. 231, Pl. VI. fig. 14), these cavities secrete a 
liquid for the moistening of the branchiae. See 
upon this subject, my observations in Muller’s 
Arch, 1842, p. 141, note 2. < 
2 See Savigny, Descript. de l’Egypte, loc. cit. 
Pl. XIII. fig. 1.5—1.8; but especially Milne Ed- 
wards, Institut. 1839, p. 152, and Hist. d. Crust. 
TIT. p. 187, and his figures in the Iconograph. du 
Régne anim. Crust. Pl. LXX. 
8 With Lithobius, there is a stigma above the 
first, third, fifth, eighth, tenth, twelfth, and four- 
teenth pairs of feet (Treviranus, Verm. Schrift. II. 
p. 29, Taf. IV. fig. 7, Taf. VI. fig. 5). With Scolo- 
pendra, the stigmata have a similar disposition 
(Kutorga, loc. cit. p. 14). 
4 Ses Savt, Isis, 1823, p. 219, Taf. II. fig. 9, a. a., 
and Bs rmeister, Ibid. 1834, p. 184, Taf. I. fig. 2, 
entirely overlooked by Treviranus. 
garded as such the orifices of a row of glands 
which are situated on the sides of the segments of 
a 1 (Verm. Schrift. II. p. 42, Taf. VIII. fig. 
, 5. 8.) 
5 The characteristic spiral filament of the Insecta 
is also not wanting here; see Kutorga, loc. cit. p. 
14, Tab. II. fig. 8. 
6 Straus, Considérat. &c. p. 307, and Burmezs- 
ter, loc. cit. Taf. I. fig. 3 (Julus). 
7 Brandt, in Miller’s Arch, loc, cit. p. 323, Taf. 
XII. fig. 4, 5 (Glomeris). 
8 Straus, loc. cit. p. 307, and Traité d’Anat. 
comp. II. p. 161; Treviranus, Verm. Schrift. IT. 
p. 30, Taf. VI. fig. 6 (Zithobius), and Muller, 
Isis, 1829, p. 551, Taf. LI. fig. 1. 
