4S 
W. P. PURCBLL. 
dages has reached its most lateral position (fig. 3). The 
anterior wall of appendage 2 has approached nearer to 
appendage 1, so that the ectodermal area («r. 8, figs. 6 
and 16), to which the entochondrite becomes attached, now 
forms the bottom of a rather wide groove lying between the 
two appendages towards their medial side. Shortly after- 
wards the three posterior provisional appendages commence 
to move towards the posterior venti-al part of the abdomen 
away from appendage 1. 
Now, as the latter retains its lateral position for the pi’esent 
and is very close to appendage 2, we find the area {ar. 8) 
between them, to which the tendon is attached, also shifting 
slightly ventrad. In fig. 27 the appendages are still in a row, 
blit the ventrad movement is commencing; in fig. 16 fa 
slightly later stage) appendage 2 has moved ventrad to the 
region comprised between the sections nos. 1-18, and the 
area of attachment {nr. 8) is no longer just behind the 
region of the two oldest furrows (/. 1 and/. 2), as it appears 
to be in fig. 27, but lies ventrally to them. When this area 
has reached the extreme postero- ventral corner of the base of 
the appendage, it remains there, while appendage 2 con- 
tinues its ventrad movement. 
The subsequent development up till after the second moult, 
is a simple one. After the completion of the reversion and 
shortly before hatching (stage 6) we find the entochondrite 
{t. 8, fig. 41) situated alongside the posterior median corner 
of the lung-complex {Ih.), just next to the medial end of the 
spiracle. The ectodermal area {ec. f. 8) to which the ento- 
chondrite is attached, is composed of elongated cells and is 
somewhat sunken-in, forming a shallow, groove-like con- 
tinuation of the spiracle (sp., fig. 18). At the second moult, 
when the young spider attains its definite form, this groove 
becomes obliterated, so that the hypodermis of the attach- 
ment area comes to lie on a level with the adjacent body 
surface and completely outside of the spiracle.^ 
’ In A^^elena liibyrinthica the groove is present in all stages 
after the time of hatching. 
