164 



Sir Ray Lankester. 



of the upper surface (fig. 1, 1, 2, and fig. 2, 2, 3, 4)- Adjoining these on the 

 right side, is the scar (tig. 2, 5) of a broader fifth flake, truncated by a sixth 

 . (see fig. 2, 6). 



The rest of the entire surface of the specimen has been trimmed by very 

 numerous blows, some of great power. These have removed all of the 

 original cortex of the flint nodule operated upon, excepting a few small 

 patches, marked cort. in figs. 1, 2, and 3. The trimming fractures of the 

 general surface have produced a few " rippled-marked " scars (fig. 2, B, S, T, 

 V, X). For the most part, the surface presents a series of irregular con- 

 vexities and concavities of a silky black appearance. 



The specimen is not iron-stained, and is entirely free from water-wear or 

 water-polish — though the fracture-edges are not sharp, but feel smooth and 

 blunted when the finger is passed over them. 



I have already mentioned the existence of a few small patches of the 

 original " cortex " or " bark " of the nodule. There is here and there — on the 

 ventral surface — (for instance, in the region about S in fig. 2) — a superficial 

 change of the black colour of the fractured flint surface to grey. This 

 decomposition of black flint usually, but not always, takes place on a broken 

 surface — commencing as a pale bluish " bloom." It becomes whiter and 

 more opaque, with longer duration of exposure. It is convenient to call 

 this change " lactescence," as I have proposed in ' Proc. Eoy. Soc.,' 1920. 



Lactescence is seen commencing as a very slight " blueing " of the fractured 

 surface in large blocks of flint at Brandon — which have been broken and 

 exposed in the knappers' yards for as short a time as six months. On the 

 other hand, fractured flints are common enough with black surface showing 

 no trace of lactescence, although fractured many thousands of years ago. 

 The conditions which favour and those which prevent this change of surface 

 have never been ascertained. 



I propose to call this implement the " Selsey rostrate." If others of the 

 same form should hereafter be found at Selsey, they may be named Selsey 

 rostrate B, C, D, and so on. 



The Selsey rostrate was not manufactured from a " blank " trimmed to a 

 tabular shape nor from a block of natural tabular flint. It is very usual for 

 palaeolithic implements of smaller size than this to have been flaked into 

 shape from a piece of flint measuring about 5 inches in length, 3 inches in 

 breadth, and 2 inches in thickness. The tabular form was either produced 

 by the preliminary "roughing out" of a nodule or, more rarely, owed its 

 initial shape to the fact that the piece selected for use was a block of natural 

 tabular flint. 



The Selsey rostrate is an unusually big and heavy implement, and was 



