These words are to be regarded as accidental variations on the ordinary laws of formation, and are no more significant of a desire to count by sixes than is the Wallachian term _deu-maw_, which expresses 18 as 2-9, indicates the existence of a scale of which 9 is the base. One remarkably interesting number system is that exhibited by the Mosquito tribe[212] of Central America, who possess an extensive quinary-vigesimal scale containing one binary and three senary compounds. The first ten words of this singular scale, which has already been quoted, are: 1. kumi. 2. wal. 3. niupa. 4. wal-wal = 2-2. 5. mata-sip = fingers of one hand. 6. matlalkabe. 7. matlalkabe pura kumi = 6 + 1. 8. matlalkabe pura wal = 6 + 2. 9. matlalkabe pura niupa = 6 + 3. 10. mata-wal-sip = fingers of the second hand. In passing from 6 to 7, this tribe, also, has varied the almost universal law of progression, and has called 7 6-1. Their 8 and 9 are formed in a similar manner; but at 10 the ordinary method is resumed, and is continued from that point onward. Few number systems contain as many as three numerals which are associated with 6 as their base. In nearly all instances we find such numerals singly, or at most in pairs; and in the structure of any system as a whole, they are of no importance whatever. For example, in the Pawnee, a pure decimal scale, we find the following odd sequence:[213] 6. shekshabish. 7. petkoshekshabish = 2-6, _i.e._ 2d 6. 8. touwetshabish = 3-6, _i.e._ 3d 6. 9. loksherewa = 10 - 1. In the Uainuma scale the expressions for 7 and 8 are obviously referred to 6, though the meaning of 7 is not given, and it is impossible to guess what it really does signify. The numerals in question are:[214] 6. aira-ettagapi. 7. aira-ettagapi-hairiwigani-apecapecapsi. 8. aira-ettagapi-matschahma = 6 + 2. In the dialect of the Mille tribe a single trace of senary counting appears, as the numerals given below show:[215] 6. dildjidji. 7. dildjidji me djuun = 6 + 1. Finally, in the numerals used by the natives of the Marshall Islands, the following curiously irregular sequence also contains a single senary numeral:[216] 6. thil thino = 3 + 3. 7. thilthilim-thuon = 6 + 1. 8. rua-li-dok = 10 - 2. 9. ruathim-thuon = 10 - 2 + 1.