KESPIRATORY ORGANS LN ARANE®. 
51 
far apart (Attus sp., fig. 20), in others, again, close 
together (Tegenaria domestica, fig. 21), or even fused to 
a single, rounded, median lobe (Lycosa Darling!) . The 
free end or ends are either sub-entire or else drawn out 
into short finger-like processes (fig. 21). Except in the 
Dysde ridse the entapophyses are more or less inclined 
backwards. 
The interpulmonary canal varies considerably, and is fre- 
quently spined and even cylindrical in the female as well. In 
the majority of cases it forms a canal of direct communication 
between the ante-chambers of the pair of lung-books, as in 
Attus floricola, but in the Lycosidm and in Philo- 
dromus this is not the case, the interpulmonary fold 
being rudimentary in the lateral part between the enta- 
pophysis and the lung-book. In many Lycosidge this por- 
tion of the fold is represented merely by a slight internal 
thickening of the cuticula [interp. jld,, fig. 19a), but in Philo- 
dromus there is a slight in-folding of the outer surface as 
well (fig. 19b) without an actual lumen being formed. The 
presence of these rudiments indicates that there was once a 
well-developed fold connecting the pulmonary sacs with the 
entapophyses, and that the pi’esent condition is a secondary 
one. 
In Argyroneta (J') the fold is well developed throughout, 
but there is no canal of communication, the two surfaces of 
the fold being closely apposed and without a lumen between 
them (fig. 19c). 
In the Dysderidae, too, there is no spinous canal of com- 
munication, although in the median part the lumen may be 
widened {interp.jid., fig. 40). In Dysdera and Segestria 
the fold is deep and well developed between the pair of enta- 
pophyses, but on the lateral side of these it is rudimentary and 
not continuous with the spiracle. In Harpactes the fold is 
much less deep than in the two other genera, and the entapo- 
physes are hardly specially distinguishable at all, being merely 
slightly deeper portions of the fold, to which the entochon- 
drites are attached. The lateral portion of the fold is, how- 
