96 SCIENCE PROGRESS 



(3) This keel or gable and the beak-like profile are still 

 more marked in the sub-Red Crag rostro-carinate, and in the 

 implements of this type found in deposits intermediate in age 

 between the sub-Crag detritus-bed and the river valley gravels, 

 the flat ventral surface and the keel are gradually extended 

 further back towards the posterior region. 



(4) This extension of the keel culminates in the production 

 of the early palaeolithic side-chopper in which a cutting-edge 

 extends continuously from the anterior to the posterior region. 



(5) The triangular section of the pointed eolithic and rostro- 

 carinate implements is transformed in the earliest palaeoliths 

 into a section which is roughly rhomboidal. This change was 

 in all probability brought about by the removal by flaking of 

 each side of the flat ventral surface of the rostro-carinate form, 

 so that a thin cutting-edge was left. 



(6) These earliest palaeolithic implements often exhibit a 

 marked resemblance in their profile to the rostro-carinate form, 

 and the remains of the dorsal or ventral surface of this latter 

 type are often left at the butt-end of the implements. The 

 remains of these surfaces have been called erroneously " lateral 

 platforms." 



(7) The most highly evolved palaeoliths are those with 

 straight symmetrical cutting edges, in which the rostro-carinate- 

 like profile has almost disappeared. 



It will thus be seen that the author is of the opinion that 

 the most primitive " eolithic " implement is linked up with and 

 related to the most symmetrical and perfect palaeolith of the 

 river-drift deposits. It is also his opinion, as a practical flaker 

 of flint, that there is no other way of making the implements 

 figured, except that described in this paper. But he does not 

 claim infallibility, and it may be that some other investigator 

 may be able to demonstrate a more accurate and better way. 



Note.— In the article on "The Oldest Flint Implements" in Science Progress 

 for January 1917, p. 435, line 20, for H in. read i}i in. 



