THE PHYTOGENY OF THE TEACHE.E JN ARANE.E. 537 
mical characters connected with the respiratory segments. 
These are (1) the presence of an anterior pair of trachem in 
place of the lung-books (apneumonous spiders), (2) the pre- 
sence of a peculiar sense-organ within the second pair of 
ti’achese, (3) the absence of the segments (corresponding to 
15 and 18, text-fig. 6) of the great, ventral, longitudinal 
muscles, so conspicuous in other spiders, belonging to somites 
9 and 10 and of the entochondrites connected with them, and 
(4) the replacement in the female of the usual receptacula 
seminis of the epigastric fold by a pair of great chamber-like 
dilations of the oviducts in the upper anterior part of the 
abdomen. 
The trachea} of Caponia and Nops have been very well 
described and figured in Simon (’93, pp. 326 and 327, figs. 294 
and 295) from drawings made by Bertkau (also reproduced by 
Lamy [:02, p. 184, figs. 24 and 25]). The following descrip- 
tion was made from a number of sections and other prepara- 
tions of Caponia spiralifera. Pure., specimens of which 
Avere collected for me at Hanover, Cape Colony, and well 
preserved in spirits by my friend, Mr. S. C. Cronwright 
Schreiner. 
The anterior pair of tracheae (p. 545, text-fig. 17, and 
fig. 9, a.tr.) are situated in precisely the same place which is 
occupied by the lung-books in dipneurnonous spiders, and 
they are evidently merely a pair of lung-books of which the 
saccules have been metamorphosed into branched tracheal 
tubules. Fig. 10 shows one of these trachem, prepared in 
caustic potash and seen from the medial side. Figs. 11 and 
12 are from sagittal sections. 
The spineless, thick-Avalled pedicel (fig. 11, ped.), which is 
continuous with the adjacent epigastric fold and much re- 
sembles it in sagittal sections, leads from the spiracle 
into an ante-chamber {tr.a.). The latter is shaped much like 
that of the lung-book of a Dysderid, being strongly inclined 
forwards and slightly outAvards, broadest near the base and 
tapering towards the higher anterior end or apex (figs. 10 and 
12). It is, hoAAever, somewhat more capacious, owing to the 
