HESPIRATOKV ORGANS IN ARANEA;. 
47 
found an oblique muscle on the medial side of the enta- 
pophysis of the pulmonary segment, which, perhaps, corre- 
sponds to a muscle {a. oh. m. 9) not observed in Attus 
f loricola. 
Ill the embryo and the growing spider the ectodermal 
areas to which the eutochondrites of the longitudinal muscles 
are attached become drawn out in the form of hollow pro- 
cesses {ec. f. 8-11, fig. 41), lined with chitin, and projecting 
into the interior of the body. These are the ectodermal 
tendons or entapophyses ' (apod ernes) of the ventral 
longitudinal muscles, and it was the purpose of the foregoing- 
paragraphs to establish their serial homology. 
Since the segments of the longitudinal muscles are each 
formed out of the entire length of the somatic wall of a 
coelomic sac, it follows that their points of attachment (or the 
entapophyses) must be intersegmental, and this is also the 
case with the points of attachment of the dorso-ventral 
muscles where they coincide with those of the longitudinal 
muscles (as, for instance, the ventral end of the muscle 
(l.r.'ia. 8, and both ends of d.r.iu. 9 and 10 in fig. 41). But 
it frequently happens in the Arachnida that the dorso- 
ventral muscles disassociate themselves at one or both ends 
from the insertions of the longitudinal muscles, and may then 
form separate external depressions, which are not necessarily 
intersegmental, but, in fact, very frequently placed more 
forwards on the face of the segment. Thus in fig-. 41 the 
muscle d. v. m. 8, although actually in contact at the place of 
crossing with the dor.sal longitudinal muscle {d. I. m. 8) of the 
eighth somite, is inserted dorsally at some distance in front 
of the intersegmental entochondrite which lies between the 
muscles d. 1. m. 8 and 9. 
VII. The Entapophyses (Ectodermae Tendons) of the 
PUDMONAHV EeGMEN'I'. 
When the entochondrites beg-iu to form at about the stage 
with five pulmonary furrows, the first pair of provisional appen- 
‘ A term introduced l>y Ray Lankester. 
