RESHRATOKY ORGANS IN ARANEA<]. 
78 
internally nearly to the apex, but its chitinous lining is 
plainly much too thick to allow it to be used for respiratory 
purposes. In Scytodes by far the greater portion of this 
chitinous lining is smooth internally (figs. 38 and 39), only a 
small part quite at the base being spined {sjji., fig. 38), but iu 
Palpimanus nearly one half is lined with hooped spines 
(fig. 37 a). In both genera the greater part of the unspined 
portion of the entapophysis is in contact with the entochon- 
drites {t. 9, fig. 37). 
The histological structure of these tracheal eutapophyses 
ajid of those of the pulmonary segment of Attus is quite 
similar. The section through the basal half of the tracheal 
entapophysis of Palpimanus (fig. 37a) should be compared 
with the spinous part {spi.) of the pulmonary entapophysis 
given in fig. 23a (in the latter the juatrix is not drawn iu), 
while fig. 37 of Palpimanus is comparable with fig. 23 of 
Attus, both passing through the places of attachment to the 
entochondrites, t. 9 and t. 8. The same fibrous hypodermis 
{hy.') and flattened smooth cuticula (c?t.) is observable in both 
figures. 
In his description of Palpimanus gibbulus Lamy says 
there are two short medial apophyses without a spinous 
lining (:02, p. 188), but his figiu’e clearly shows that the two 
trunks are confluent for the greater part of their length and 
separate only towards the apex. Lamy evidently considers 
the confluent portion to be part of the vestibule. In other 
places, too (:01b, p. 178; :02, p. 174), he states that in all 
these forms the medial trunks ai’e reduced to the unspined, 
terminal, tendinous (i.e. fibrous) part found at the end of the 
medial trunks in Epeira, etc., by means of which the attach- 
ment to the entochondrite is effected, while the whole portion 
of the trachea in Epeira between the entochondrite and the 
vestibule are said to be absent in Palpimanus. 1 cannot 
consider this view to be quite correct, for the entire median 
process in Pal piman u s and Scytodes, including the un- 
paired part in the former and the spinous portion in both, 
constitutes the entapophyses, and the spinous portion lying 
