KESPIRATOKY ORGANS IN ARANE^E. 
71 
system appears to be derived from the teiidinal 
portion of the trachea, and there is no distinguish- 
able trace left of the lateral trunks, ■which may be 
homologised with the pulmonary sacd This leads us 
to the conclusion that the ti'acheal systems of Argyroneta 
aud the Dysderidse, although superficially closely resem- 
bling one another, are yet apparently not homologous struc- 
tures. 
The tracheae in the Scytodidae, Palpimanidae and Filistatidae. — 
The trachefe of these three small families possess a peculiar 
interest, inasmuch as Lamy has shown that their medial 
trunks are uon-respiratory and serve solely as entapophyses 
for the attachment of the entochondrites. Bertkau (’78) 
observed that the medial trunks were reduced to an unpaired 
median rudiment in Scytodes, only the lateral ones being 
developed, but our knowledge of the trachefe in the other 
forms is due to Lamy (;00, ;01b, :02). 
The most interesting is the tracheal system of Filistata, 
of which I reproduce Lamy’s figure (:02, p. 173, fig. 12), as I 
have no material of this family at my disposal. Here, accord- 
ing to Lamy’s description, the spiracle is very broad and 
placed about midway between the interpulmonary fold and the 
spinners. The two short lateral trunks (Z. tr.) are pointed 
sac-like and of the simplest form, exactly as a pulmonary sac 
would appear if it lost its saccules. The four trunks are con- 
nected at base by an intertracheal fold with spines in its 
deepest part (which no doubt forms a canal of communica- 
tion). The two entapophyses (ec. t. 9), too, have some internal 
spines in their basal part, but are otherwise unspined, while 
their free ends are jagged and tendon-like. If we compare 
this text-figure Avith the figure of the pulmonary 
system of Attus (fig. 20) and leave the saccules 
out of account, the parallel between the two 
' MacLeod’s (’ 82 , p. 785, and ’ 84 , p. 29) view that the trachea of 
Argyroneta is nothing else than the dorsal chamber of the second 
pair of lung-books of a My gale, enormously developed, is certainly 
incorrect. 
