The Scotchman, MacLennan, who discovered totemism and exogamy for science, 16 refrained from publishing his views of the origin of totemism. According to a communication of Andrew Lang 17 he was for a time inclined to trace totemism back to the custom of tattooing. I shall divide the accepted theories of the derivation of totemism into three groups, α) nominalistic, β) sociological, γ) psychological.