34 Fi-oceediiig.^ of tire Mo/jdl Societ/j of V'tcforla. 



largei" section is generally sniouth and marked with pittings 

 crowded into irregular bands or patches enclosing smooth ellip- 

 tical centres. The smaller section shows the peculiar corruga- 

 tions commencing immediately under the peripheral ridge, but 

 gradually fading away as the centre of the section is approached. 

 The pittings are also present, but to much lesser extent and more 

 equally distributed. It also shows marks or short grooves, in 

 their arrangement somewhat resembling Hebrew characters, 

 commencing at a slightly raised centre and radiating in six irre- 

 gular lines towards the ridge. These grooves are also noticed in 

 other specimens. The smooth elliptical centres referred to above 

 are also outlined by fine groovings in places passing through the 

 pits. In some instances the pittings themselves have the appear- 

 ance of being drawn out, forming short grooves parallel to the 

 fine markings. 



Another feature is that some of the pits are contained within 

 others. The interior of the obsidianite, which is slightly egg- 

 shaped, has its greater diameter of 47 '5 mm. in the direction of 

 the smaller outside diameter. The other inside diameter 

 measures 44-5 mm. It is perfectly smooth and has a high polish 

 The obsidian is quite dense, with the exception of a few scattered 

 vesicles, and is of a brownish colour in transmitted light. One 

 or two points in connection with this specimen are worthy of 

 mention. In general external form it diilers only in being 

 rather more spherical than other solid specimens, and in this 

 respect, to all intents and purposes, they may be regarded as 

 identical. This being so, it is evident that the presence of the 

 cavity cannot have had any influence of consequence upon its 

 configuration. The vesicles contained in the wall are spherical 

 and small and few in number. Had the obsidianite been pro- 

 duced from a fragment of lava rich in gaseous components, the 

 walls would surely have been highly vesicular, with a tendency 

 for the vesicles to be drawn out in a direction coincident witli 

 the surface. 



A striking feature in this specimen is the remarkable difference 

 shown between the two sections. They are sharply defined by 

 the ridge, as if two diverse agencies were at work in their forma- 

 tion. With regard to an explanation for the production of the 

 button-shaped, or in fact any, specimens it must to a great 



