THE PHYLOGENY OP THE TRACHEJ5 IN AfiANE.E. 529 
extent of the abdominal segments in the tliree families much 
resembles that in the Mygalomorphse. 
Dysderidfe. — The lung-books in the Dysderidse have 
few leaves. I counted about thirteen in Harpactes (in 
sections), but there are more in Dysdera and Segestria 
senoculata (Bertkau [’72] records only ten to twelve for 
Segestria). The ante-chamber {pulm. a.) is strongly 
inclined forwards from the base at an angle of 40° — 50°, 
and is evenly curved forwards in Harpactes (PI. 28, fig. 5), 
but almost straight in Dysdera and Segestria (p. 530, text- 
fig. 7). It is spined on its posterior wall except quite 
interiorly, where a muscle (text-fig. 7, No. 11) is attached. 
Text-fig. 3. — Abdomen of Dysdera sp., ad. ? (magn. 3). 
Text-fig. 4. — Abdomen of Calculus bicolor, ad. ? (magn. 
10 ). 
Text-fig. 5. — Abdomen of Caponia spiralifera, ad. 9 
(magn. 3.) 
sp'., sp". Spiracles of the first and second respiratory segments. 
7 — 10 denote the extent of the seventh to tenth somites. 
The peculiarities of the epigastric fold have already been 
described (:09). 
The well-known tracheae (p. 551, text-fig. 19) have been 
described by several authors (see Lamy [:02, pp. 180 — 183] 
for some excellent figures of Dysdera and Segestria), and 
I have given a summary of their structure with some addi- 
tional observations on the entapophyses and muscles con- 
nected with them (:09). 
In order to ascertain anatomically whether a trachea or a 
