THE PHYLOGENT OP THE TEACHEiE IN AEANE^. 519 
The Phylogeny of the Tracheae in Araneae. 
By 
W. F. Purcell, Pli.D., 
Bergvliet, Diep River, near Cape Town. 
With Plate 28, and 21 Text-figures. 
Introduction. 
In an excellent paper on the tracheae of spiders E. Lamy 
(:02) has given an account of the tracheae of thirty families 
of Araneae, so that only four small and comparatively rare 
families, comprising 1 — 3 genera each, remain, of which the 
tracheae are still unknown. It is now possible, therefore, to 
consider the tracheal systems of the Araneae as a whole 
from a phylogenetic point of view, and as I barely touched 
upon this point in my paper (:09) on the development and 
origin of the respiratory organs in spiders, I propose to make 
it the subject of the present paper. 
Lamy has made it perfectly clear that the degree of com- 
plication of a tracheal system, as regards the manner and 
extent of the branching and the structure of the internal 
armature (spines, spiral thread, etc.), cannot be used as a 
family character, since we may find the most varied degrees 
of complication amongst the different genera of one and the 
same family (e. g. in the Uloboridee, Thomisidae, Age- 
1 enidae, Clubionidm, Attidae, etc.). Lamy concludes from 
this that the tracheal apparatus is evolved separately in each 
family and not in the Araneae as a whole (p. 265) and this 
statement may, I think, be accepted as in general correct. 
