280 
ARACHNIDES. 
several sacs, and then of a second stomach or dilatation sur- 
rounded with silk. According to the observations of M. Leon Dufour 
— Ann. des Sc. Phys.VI — it occupies the greater part of the abdomi- 
nal cavity, and is immediately enveloped by the skin. It is of a 
pulpy consistence, and is formed of granules*, whose individual ex- 
cretory ducts unite in several hepatic canals, which pour the secreted 
matter into the alimentary tube. In the middle of its superior sur- 
face is a depressed line, where the heart is lodged, and which divides 
that organ into two equal lobes. Its form, like thatof the abdomen, va- 
ries according to the species ; thus in the Epeira sericea its contour is 
festooned. In this subgenus, as in the Lycosa tarentula, its surface is 
covered with a Avhitish coat split into areolae, which, in several species, 
are easily perceived through the glabrous skin ; they may be seen 
obeying the impulse communicated to them by the systole and diastole 
of the heart. Both sexes frequently eject from the anus an excre- 
mentitious fluid, part of which is milk-white-, and the remainder black 
as ink. 
The nervous system is composed of a double cord occupying the 
median line of the body, and of ganglions which distribute nerves to 
the various organs. M. Dufour has not been able to determine the 
number and disposition of these ganglions, but from the figure of this 
system given by Treviranus — Veber deninnern, bau des Arachniden, 
tab. V. fig. 45 — there are but two. The observations of the latter 
will also supply the want of those relative to the organ of the circu- 
lation by M. Dufour, which, according to him, ajjpears to consist of 
a simple dorsal vessel, as well as Avith respect to the testes and 
spermatic vessels, on which he is totally silent. 
I'lie dorsal region of the abdomen in several Araneides, those 
especially which are glabrous or but slightly pilose, exhibits depressed 
points varying both in number and arrangement. M. Dufour has 
ascertained that these little orbicular depressions are caused by the 
insertion of filiform muscles, which traverse the liver, and Avhich he 
has also observed in the Scoiqfions, 
I'he one or two pairs of pulmonary sacs are indicated externally 
by as many yellowish or whitish spots near the ventral base, and 
immediately after the segment, which, by means of a fleshy thread, 
unites the abdomen with the thorax. Each pulmonary bursa is formed 
by the superposition of numerous, triangular, white, and extremely 
thin leaflets, which become confluent round the stigmata, and Avhose 
number exactly equals that of the pulmonary sacs. When there are 
* The liver of the Scorpions is composed of pyramidal and fasciculated lobules, a 
circumstance which seems to announce a more advanced degree of organization. 
