§ 312. THE ARACHNOIDAE. 885 
ramify through the whole body like those of insects, there are three pairs 
of stigmata. With the Phalangidae, the trachean system is highly 
developed, arising from two stigmata concealed under the coxae of the 
posterior legs, each of which has a horny valve. The two large trunks 
given off from these stigmata, run obliquely to the cephalic extremity; they 
intercommunicate by a transverse anastomosis, and give off, in all direc- 
tions, numerous branches which are spread over the abdominal viscera, and 
penetrate even the palpi and legs. 
With many of the Araneae, there are, on the under surface of the abdo- 
men, two orifices which lead into two pulmonary sacs, beside two other 
openings belonging to the trachean system. With Segestria, Dysdera,™ 
and Argyroneta, there arise from these two stigmata two large trunks 
surrounded by a kind of horny trellis-work. From the extremity of these 
trunks are given off innumerable, very small tracheae, which are un- 
branched and without the spiral filament. They are disposed in tufts, and 
are distributed, some in the abdomen, and others in the cephalothorax, 
penetrating even to the extremity of its members. With Salticus, and 
Micryphantes,® the two stigmata are situated at the posterior extremity 
of the body, far removed from the pulmonary sacs, and send off, directly, 
two tufts of unbranched tracheae, which are distributed exclusively to the 
abdominal viscera.® There is, with the other Araneae, a trachean 
system, very imperfect it is true, which has hitherto been overlooked by 
anatomists. Directly in front of the spinuerets, there is, with most species, 
a transverse fissure difficult to be seen, which leads into a very short 
trachean trunk. From this trunk are given off four simple tracheae 
which, singularly, are not cylindrical, but are flattened, riband-like, and 
without a trace of a spiral filament; these extend, with a gradual attenua- 
tion, to the base of the abdomen. These riband-like, silvery tracheae are 
composed of a thin, but solid, homogeneous membrane, which is enveloped 
by a soft, transparent pellicle corresponding to a peritoneum. The air 
received into these organs is separated into as fine portions as that of the 
lungs. These tracheae differ therefore, prominently, from those of the 
other Arachnoidae. 
ignorant of their existence, and even lately, that 
Tulk (Annals of Nat. Hist. XV. p. 57) should 
have failed to see them with Obistum. 
4 See Miller, Isis, 1828, p. 711, and Milne Ed- 
wards, Régne anim. Illustr. Arachnides, PI. IT. 
5 Treviranus, Verm. Schrift. I. p. 32, Taf. IV. 
fig. 19, and Tuk, loc. cit. p. 327, Pl. V. fig. 33. 
6 Dugés, in “Le Temps,” 1835, No. 1942, 
Feuilleton, Acad. d. Sc. Séance du 9 Fevrier, or 
Froriep’s neue Notiz. XLIII. p. 231, or Ann. d. 
Sc. Nat. VI. p. 183, and Régne animal, Arach- 
nides, Pl. III. fig. 4, V. fig. 4. See also Owen, 
Lectures, &c., p. 259, fig. 112. . 
7 Grube, loc. cit. p. 300, and Menge, loc. cit. p. 
22, Taf. I. fig. 6-14. 
8 Menge, loc. cit. p. 23, Taf. I. fig. 15. 
9 I have had an opportunity to satisfy myself of 
the existence of this interesting trachean system 
with Segestria, Argyroneta, Salticus, and Micry- 
phantes. I should also add that the principal 
trunks are flattened, and that the contained air is 
«x [§ 312, note 10.] See also for these anomalous 
tracheae, Blanchard (loc. cit. Ann. d. Sc. Nat. 
XII. 1849, p. 345), who regards them as only 
33 
finely divided, while that in the cylindrical tra~ 
cheae given off from these trunks, forms a continue 
ous column. 
10 [ have found this trachean system with 
Epeira, Tetragnathus, Drassus, Clubiona, 
Theridion, Lycosa, Diomedes and _ severak 
others. I have been unable to perceive it in 
individuals escaping from the egg. Thomisus 
viaticus is the only species in which the four 
flattened trachean trunks are ramified, and tnus 
serves as the passage to the most highly developed 
trachean system of Salticus. -By direct light, 
they appear black, and thus it is possible that they 
may have sometimes been taken for urinary canals. 
But this error is unnecessary, for these last vessels. 
burst from the slightest pressure and etfuse granu— 
lar contents, while the tracheae under such treat-. 
ment become transparent, their contained air 
making its escape, and when the pressure is with— 
drawn they resume their black color.* 
elongated pulmonary sacs ; but especially Leuc- 
kart (Ueber den Bau und die Bendeutung der sog. 
Lungen bei den Arachniden, in Siebold and Kélli- 
