548 
\V. F. rUKCELL. 
(No. 13) to the upper edge of the posterior intertracheal 
fold along its whole ex^^tent, but the descending strands 
(No. 35) on the anterior side of this fold are only met with in 
the lateral part, being absent from the median part of tlie 
fold. A similar parietal muscle is met with in the Dys- 
deridm and Oonopidm, differing only in so far that the 
lateral ascending’ strands (No. 13, p. 530, text-fig. 6) are 
attached to the large entochondrite (/. 9) of the tracheal 
segment.^ 
I could find no trace of the usual medial longitudinal 
muscles corresponding to 15 a,nd 18 in the Dysderidte, and 
connecting the anterior entapophysis {ec.t. 8) with the spin- 
ners on the medial side of the trachem. In fact, the only 
muscle connecting- the respiratory segments with the spin- 
ners, and lying inside of the abdominal muscular sac, is the 
slender muscle 23n, which, however, lies on the lateral side 
of the trachea, and is, I think, probably homologous with 
muscle 23 of the Dysderidae. This little muscle in 
Cap on i a divides posteriorly into at least two muscles and 
the most ventral of these branches,” corresponding to 27 or 
28 of Segestria, is attached to the lateral (S') or middle 
( ?) part of the anterior side of the mesial anterior spinners, 
which I take to represent the anterior pair of the Dysde- 
ridm. Anterioidy 23a unites with three other small muscles, 
30a, 32, and 33, at a ])oint .r at the base of the lateral side of 
the abdominal tracheal trunk (ahd.tr.). The four muscles 
are here in contact with the trachea, and their fibres inter- 
mingle without forming an entochondrite. One of them, 
30a, passes on to the apex of the entapophysis (ec.t. 8), and 
’ The alxloniinal muscular sac in other spiders has Ijeen descril)ed 
l>y various authors, particuhirly l)y Causard ('96, pp. 22-24, pi. iii, figs. 
1 and 2). and more recently liy Lamy (: 02, p. 158, pi. vii). Of the 
muscular nature of its fibres there can be no doubt whatever, as the 
typical transverse striations may he frequently observed in the 
Oaponiida“. the Dysderida, and other forms. 
- I could not make out where the posterior ends of the dorsal branch 
or branches were attached. 
