THE PHYTOGENY OP THE TRACHEAE IN ARENEJE. o47 
(inserted next to 8, and just beliind but sligditly lower than 
dO). (See also fig. 8, m. 37.) 
The most remarkable features of tliis muscular system are 
the complete absence of all entochondrites, and as well as of 
those segments of the great, ventral, longitudinal muscles 
which belong- to the second respiratory and the anterior 
spinner segments (somites 9 and 10). 
The muscles 1 — 10 are identical in the Dysderidm and 
Caponiidm, 1 — 4, however, being attached in the latter 
directly to the anterior side of the entapophysis {ec.t. 8) 
without the interposition of an entochondrite. No. 4 is a 
very broad atid powerful muscle, being attached, as already 
explained, to the whole anterior side of the lateral deflected 
lobe (1.) of the epigastric fold, and is represented in the 
IJysderidm by several feeble strands only. The muscles 
1 — 3 are attached in Caponia to the prominent lateral 
entapophysis (ecJ. 8), which is, therefore, plainly homologous 
with the entapophysis of the pulmonary segment of the 
Dysde ridm (p. 530, text-fig. G, ec.t. 8) and other dipneu- 
monous spiders. It may be noticed that in Caponia this 
entapophysis has completely taken the place of the ento- 
chondrite (t. 8) of the Dysderidae, its anterior surface being 
correspondingly expanded to take the four large muscles. 
The three muscles, 8, 11, and 30, which in the Dysde- 
ridm are attached to the enchondrite t. (p. 530, text-fig. 7), 
are also represented in Caponia, only here the lateral ends 
of these muscles are attached separately to the body integu- 
ment, and are more dispersed (although still quite close 
together) owing to the absence of the entochondrite, and 11 
runs parallel to the transverse plane, while in Segestria its 
fibres lie in sagittal planes. 
The parietal muscle 12 is a part of the abdominal muscular 
sac which lies immediately within the outer hypodermis and 
envelops the intestines. The ventral strands of the sac are 
here longitudinal, and form a continuous layer from side to 
side, where they are again continuous with the lateral walls 
of the sac. Anteriorly the ventral strands of the sac ascend 
VOL. 54, I’ART 4. NEW SERIES. 39 
