210 



developed from a "gibber" stone in its natural condition. 

 These have evidently been selected on account of their size 

 and shape being adaptable, after modification by chipping, 

 for certain useful purposes. It is not always an easy matter 

 to assign some particular form to its proper place in this 

 classification, on account of the influence of solar heat in 

 effecting fractures in fine-grained siliceous rocks. Sun-flaked 

 rocks sometimes show a curved and smooth face on the plane 

 of fracture, which simulates conch oidal fracture, but is 

 destitute of a percussion bulb. When a face of this kind 

 occurs, it must be doubtful as to whether the flaking has been 

 done by the workman, or whether the latter has availed 

 himself of a fragment which had already been severed from 

 the parent rock by solar action. The element of doubt, as to 

 the origin of the fragment, has no bearing on the evidence of 

 human workmanship in the subsequent treatment of the stone, 

 which, in many cases, is beyond doubt. 



2. Whether a conchoidal bulb be shown or not, there 

 is, almost invariably, a flat face on the one side (which is the 

 ventral or under-side), and a, more or less, raised surface on 

 the other (which is the dorsal or upper-side). In certain 

 prehistoric stone implements of Neolithic Age, as well as in 

 the case of the stone implements of the existing tribes of 

 Aborigines in Australia, this flat under-side forms a part 

 jbf the manipulation and is conchoidal in character. In the 

 tableland implements, it seems probable that some owe their 

 flat under-sides to natural causes, either by jointing or some 

 other form of natural fracture. 



3. The chipping is, for the most part, developed on the 

 convex or upper-side of the implement, and sometimes com- 

 pletely surrounds the specimen. If the curvature of the edge 

 requires that, for the making of a straight cutting edge, the 

 chipping should, in places, be developed on the flat, or under- 

 side, it is chipped on that side also. This is not peculiar to 

 the type now under description, but examples of this kind 

 occur in the stone implements of all ages — it is an evidence 

 of design. 



4. The tableland examples are frequently of a size that 

 is much in excess of the usual type of implements found 

 in other parts of Australia. 



5. Pointed implements are particularly common. The 

 point is sometimes developed as a prominence between two 

 concave scrapers and was no doubt intended for use, as well 

 as the scrapers with which it is associated in the same 

 implement. It is sometimes improved by a deep notch on 

 pne side, as in fig. 1, pi. xv., and pi, xvi., and is sometimes 

 claw-shaped, as in fig. 1, pi. xii. The association of "beaks" 



