THE PHYLOGENY OF THE TRACHEA! IX ARAXE.E. 531 
part of one is homologous Avith a lung-book or with an 
entapophysis it is necessary first of all to identify the 
entapophyses of the great longitudinal muscles. These 
entapophyses, as I have shown for Attus and Agelena 
(’95, :09), arise in various abdominal segments as invagina- 
tions on the posterior side of the provisional appendages, 
while the invaginations Avhich form, or correspond to, a 
pulmonary sac or ante-chamber always lie to the lateral side 
of the entapophyses. In the two segments bearing the 
spinners in Attus and Agelena the entapophyses are 
attached at the posterior, medial, basal corners of the 
anterior and posterior spinners. For the identification of 
the entapophyses anatomically a knowledge of the abdominal 
muscles connected with the respiratory segments is necessary, 
and I have given the two accompanying diagrams (text-figs. 
G and 7) to illustrate these muscles and their entochondrites 
in a typical Dysderid. 
Ijist of the Entochondrites and Muscles in Text-figs. G and 7. 
t. Small entochondrite on the lateral side of the trachea 
and attached to the fold of the integument, /‘d. 2. 
t'. Fntochondrite between the muscles 23 and 21, etc., but 
not attached to the integument. 
/. H. Large entochondrite situated on the medial side of the 
pulmonary aute-charnber and attached to the epigastric- fold. 
t. 9. Corresponding entochondrite of the tracheal segment, 
situated on the medial side of the trachea. 
Muscles. 
1 and 2. From the entochondrite C8 to ujtper and middle 
part of side of abdominal pedicel. 
3. Longitudinal from the entochondrite L8 to the cephalo- 
thorax. 
4. From the entochondrite L8 to ventral integument of 
pulmonary segment. 
VOL. 54, PART 4. — Xltw SERIES. 
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