554 HARPOON-BARBS AND TRIANGULAR KNIVES. 
huge sturgeon were caught at Thetford in 1715 and 1 737,. 
even in late Neolithic times — the period to which these 
implements belong — there may have been prey for harpoonists 
in the fresh or brackish waters of the Little Ouse valley. 
There is another class of implement fairly common in 
Ireland, but in England almost confined to the arenaceous 
areas of south-west Norfolk and north-west Suffolk, some of 
which may perhaps have been used as harpoon-barbs. These 
implements are now generally known as triangular knives, 
though formerly classed as arrowheads, and American archaeolo- 
gists have made a line of demarcation by classifying as knives 
those with rectangular bases, and as arrowheads those with 
oval bases. Such triangular implements have been found at 
Gurob, Egypt, in remains of the Xllth Dynasty (2600 B.c.), 
are very common in the United States, Ireland and Scandi- 
navia, but rare in Britain. Sir John Evans figures an almost 
perfectly triangular form, of rare occurrence, from near 
Lakenheath. It is neatly chipped over both faces, which 
are equal in shape. In the Salisbury Museum there are 
triangular arrowheads and others hollowed out at the base, 
remarkable for the fineness of the surface chipping and the 
extreme correctness of outline. Most of these are now 
classified as triangular knives. With the exception of one 
found by Mr. W. A. Dutt on Bungay Common, all the East 
Anglian examples I have seen came from the “ breck ” 
district. I have examined about 50 specimens and find 
that the greatest length of any one side is 2 inches, and that 
the average is between ij in. and i\ in. They may be 
divided into three classes : (1) those chipped all over both 
surfaces, (2) those worked on two edges only, but on those 
edges worked both sides, and (3) those with hollow bases. 
Those chipped all over both surfaces generally give evidence 
of most skilful workmanship and are frequently equilateral. 
They are most beautiful little implements and may have been 
used as hafted knives or as arrowheads. A sub-division is 
chipped around the three edges on both sides, but not on the 
surfaces. Those that are hollow-based are generally chipped 
only on the edges. The most interesting examples, however, 
