THE PHYLOGENY OF THE TEACHE.T: IN ARANEH:. 533 
23. Longitudinal connecting the entocliondrites t. and t' . 
24. Longitudinal from the entochondrite t' . to the spinners, 
dividing posteriorly into 25 and 26. 
25. Two muscles from 24 to anterior lateral angle of large 
posterior spinner. 
26. From 24 to posterior lateral angle of anterior spinner. 
27. From the entochondrite t'. to anterior lateral side of 
anterior spinner. 
28. From the entochondrite t'. to anterior side of anterior 
spinner (inserted behind 22). 
29. From posterior end of the cephalothoracic tracheal 
trunk ceph.. tr. (inserted just below the origin of the short 
abdominal branch) to ventral integument of abdomen. 
30. Subtransverse connecting the entocliondrites t.S and t. 
31. Connecting the entochondrites ^9 and t'. 
(Tsvo other muscles of the female of Harpactes are given 
in PI. 28, fig. 3). 
3’he part of the epigastric fold (text-fig. 6, ec.t.S) to which 
the entochondrite t.S is attached, plainly corresponds to the 
entapophysis of the pulmonary segment in other dipneu- 
monous spiders (see my paper :09, fig. 41, ec.t.S), but the 
identity of the corresponding entapophysis of the tracheal 
segment is not at first sight so evident, since there are two 
entochondrites, one on each side of the trachea, and two sets 
of longitudinal muscles, both connected with the entochon- 
drite t.S. In fact, the whole muscular system of the ninth 
and tenth somites is very different to that of Attus, Age- 
lena, Epeira, etc., which is, of course, due to the circum- 
stance that in the latter the relative lengths of the two 
somites are exactly reversed. From the fact that the muscles 
19 — 21 of the medial set in Segestria (text-fig. 6) are con- 
nected with the medial and postero-medial sides of the 
anterior and posterior spinners, while the muscles 25 — 27 of 
the lateral set (text-fig. 7) are connected with the lateral 
side of the same spinners, it is evident that the entochon- 
drite t.9 is the one which in the tracheal segment corresponds 
to the entochondrite t.S of the pulmonary segment. The 
