NOTES ON ANTARCTIC ROCKS. 491 
to overestimate its importance as bearing on the whole subject 
of the geography and geology of Antarctica ; and we here desire 
to express to him our warmest thanks for his courtesy in allowing 
us the privilege of examining and describing his collections. Our 
thanks are also due, for help kindly given us when preparing 
material for this paper, to the following : .—_Mr. H. 8S. W. Crummer, 
the Hon. Treasurer of the New South Wales Branch of the Royal 
Geographical Society of Australia; Mr. E. F. Pittman, Assoc. B.S.M., 
the Government Geologist ; Mr. G. W. Card, Assoc. R.S.M., Miner. 
alogist ; Mr. W. S. Dun, Assistant Paleontologist and Librarian 
to the Geological Survey of N. S. Wales; and to the following 
geological students of the University of Sydney: :—Miss Montefiore, 
Miss Flavelle, Miss Haslam, Miss Noakes, Mr. H. J. 8. Brook, 
and Mr. Graham Officer, B.Sc. 
EXPLANATION OF PLATES. 
PLATE XIII. 
Fig.1. Triply-twinned grain of felspar showing Carlsbad, Mannebach 
and Albite types. Two of the sectors are shown extinguis 
Fig. 2a. Basal section of topaz, showing usual position of a axes, 
the sign being positive. 
Fig. 2b. Section of topaz, in Granulitic Aplite, A. No. 4, showing 
position of optic axes, the sign being negative. 
Fig.3. Prisms of rutile and anatase from Granulitic Aplite, A. No. 4, 
Fig. 4. Crystal of aiden from Olivine Basalt, A. No. 7, with inter- 
8town meshwork of magne 
Figs. 5,6. Pseudomorphs of hornblende composed of granular augite, 
colourless isotropic material, brownish-yellow olivines, and dark none 
a inclusions. These latter may be oxides of iron or possibly 4 
ate allied to ilvaite. Some of the hornblende remains in ¢ ach. 
The augite granules are optically continuous and have the plane of 
try and vertical axis coincident with those of the horblende. 
a. 7. A portion of Fig. 6 enlarged; the dotted grains represent 
Fig. 8. Polished surface of basalt B. No. 8, at right angles to axes of 
nitrate i i ne softer kernels of these lumps represe ented by lighter 
Repeats which irregular cracks radiate through the surrounding 
