540 
W. F. PUECELL. 
somewhat flattened dorso-ventrally at their origiu, only to 
divide into a couple or more cylindrical tubes in the next 
section, e.g. the lowest tube in text-fig. 9. The tracheal tubes 
are not long, being only about three or four times the length 
of the ante-chamber, and they do not enter the abdominal 
pedicel. All, or nearly all, are several times branched, the 
branches becoming slenderer towards the apex where they 
frequently end in a short fork (fig. 10). They are either 
cylindrical or compressed, being then mostly flattened dorso- 
ventrally, like the saccules of lung-books, and are lined inter- 
nally, except quite at the base, with a tine, probably spiral, 
thickening of the cuticle, just like the tracheal tubules of the 
Dy sd erid ae, etc. The bi-nucleate columns of the original sac- 
cules have, of course, disappeared. The anastomosing spines 
of the ante-chamber enter the bases of the tubes for a 
short distance and the free edges of the tubes bordering on 
the cavity of the ante-chamber have very much the appear- 
ance of those of pulmonary saccules in sagittal sections (cf. 
fig. 5 of the lung-book of Harpactes with figs. 11 and 12 
of the trachete of Caponia). In a young specimen examined 
the tubules were much fewer than in any of the adult speci- 
mens, hence it is evident that the}'^ increase in number with 
the growth of the spider. 
In addition to the above there is a small group of tubules 
which start from a slightly projecting portion of the ante- 
chamber at its base on the medial side. This group is com- 
posed of a bunch of four tubules, which may, however, sub- 
divide into several more. They take at first a transverse 
medial direction and then bend and run some distance back- 
wards on the lateral side of the second pair of trachem 
(fig. 9, med. tub.). This group of tubules has no equivalent 
in the lung-book of theDysderidm and is to be looked npon 
as a new formation. They may, perhaps, be the posterior 
group of six tubules represented in one of Bertkau’s figures 
(Simon, fig. 294, or Lamy, fig. 25). 
The second pair of trachea? of Caponia forms per- 
haps the most complete and extensive tracheal system known 
