The last of these scales is an unusual combination of decimal and vigesimal. In the even tens it is quite regularly decimal, unless 80 is of the structure suggested above. On the other hand, the odd tens are formed in the ordinary vigesimal manner. The reason for this anomaly is not obvious. I know of no other number system that presents the same peculiarity, and cannot give any hypothesis which will satisfactorily account for its presence here. In nearly all the examples given the decimal becomes the leading element in the formation of all units above 100, just as was the case in the Celtic scales already noticed. Among the northern tribes of Siberia the numeral scales appear to be ruder and less simple than those just examined, and the counting to be more consistently vigesimal than in any scale we have thus far met with. The two following examples are exceedingly interesting, as being among the best illustrations of counting by twenties that are to be found anywhere in the Old World. TSCHUKSCHI.[352] 10. migitken = both hands. 20. chlik-kin = a whole man. 30. chlikkin mingitkin parol = 20 + 10. 40. nirach chlikkin = 2 x 20. 100. milin chlikkin = 5 x 20. 200. mingit chlikkin = 10 x 20, _i.e._ 10 men. 1000. miligen chlin-chlikkin = 5 x 200, _i.e._ five (times) 10 men. AINO.[353] 10. wambi. 20. choz. 30. wambi i-doehoz = 10 from 40. 40. tochoz = 2 x 20. 50. wambi i-richoz = 10 from 60. 60. rechoz = 3 x 20. 70. wambi [i?] inichoz = 10 from 80. 80. inichoz = 4 x 20. 90. wambi aschikinichoz = 10 from 100. 100. aschikinichoz = 5 x 20. 110. wambi juwanochoz = 10 from 120. 120. juwano choz = 6 x 20. 130. wambi aruwanochoz = 10 from 140. 140. aruwano choz = 7 x 20. 150. wambi tubischano choz = 10 from 160. 160. tubischano choz = 8 x 20. 170. wambi schnebischano choz = 10 from 180. 180. schnebischano choz = 9 x 20. 190. wambi schnewano choz = 10 from 200. 200. schnewano choz = 10 x 20. 300. aschikinichoz i gaschima chnewano choz = 5 x 20 + 10 x 20. 400. toschnewano choz = 2 x (10 x 20). 500. aschikinichoz i gaschima toschnewano choz = 100 + 400. 600. reschiniwano choz = 3 x 200. 700. aschikinichoz i gaschima reschiniwano choz = 100 + 600. 800. inischiniwano choz = 4 x 200. 900. aschikinichoz i gaschima inischiniwano choz = 100 + 800. 1000. aschikini schinewano choz = 5 x 200. 2000. wanu schinewano choz = 10 x (10 x 20).