THE PHYLOGENY OF THE TRACHE.E IX ARANE.E. 539 
Text-figs. 8 — 15.— Eight consecutive transverse sections through 
an anterior trachea of Caponia spiralifera. commencing 
with the most posterior one of the eight (see PI. 28, fig. 11). 
spi. Anastomosing spines of ante chamber. tr. a. Ante- 
chamber. (Tlie lateral side of the trachea is on the right of 
each figure.) Magn. 192. 
greater elongation of its ventral side. Internally the ante- 
chamber is lined with anastomosing sjiines [■'‘pi.), except 
laterally near the base of the upper (posterior) wall, where 
there is a fold [J'd.) to which a short muscle (No. 11 in text- 
fig. 17, p. 545) is attached, exactly as in the Dysderidie. 
Nearly all the tracheal tubules, except a medial group of 
four, spring from the ascending anterior side of the ante- 
chamber and run forwards. They occupy exactly the posi- 
tion of the saccules of a lung-book (c.f . text-figs. 7 and 17) 
from which they are plaiidy derived. In fact, if the 13 or 14 
saccules of the lung-book of a Harpactes (fig. 5) weie each 
divided longitudinally into several tubules, Ave should have 
the condition found in Caponia. To illustrate this, as well 
as the arrangement and origin of the tubules on the anterior 
wall of the ante-chamber, 1 have given a series of consecutive 
transverse sections (text-figs. 8 — 15), of which text-fig. 8 
through the ante-chamber represents the most posterior of 
the eight. It will be observed that the tubes are frequently 
