163 
E the Psi gases would be dissolved or condensed. 
e process would have initiated before final and complete 
consolidation took place, and the accompanying excess of 
For the Cape "Willoughby quartz-tourmaline nodules re 
following data are in accord with the hypo outlined in 
the previous pages for their manner of origin:— 
(1) The pneumatolytic origin of the tourmaline: ; 
(2) The development of the nodules in, and their 
practical pectus to, the finer-grained variety 
of the red aplit 
(3) The doripés God: 'and texture of the nodule in 
which the tourmaline is replacing the felspar is 
identieal with that of the associated aplite. 
(4) The general ellipsoidal character of the nodules. 
As denoting their manner of origin, it is suggested that 
the name ‘Pneumatolith” ds attached to such pseudo- 
segregations occurring in ran dena ise owe their existence 
primari my to pneumatolytic 
previously noted, the exact siet of the tourmaline 
to the orthoclase = associated with it is not haces. but 
Scopical examination. A number of these have ds been 
described ed by Waller and Hogg.) 
The Se ades examined by the writer consist essentially 
of quartz and Ke imperet felspar being absent. Macro- 
Zr it has been recognized in one nodule, and is 
represented by kaolin 
ELI eo s esc i duit 
06 Loc. cit., Sup., p. 543. 
pp. Mise. and Hoge: Papers Proc. Roy. Soc. Tas., 1902, 
i 
