しらゆきひめ 'Snow White'

Question

I am trying to understand the title of a tale.

• しろ 'white'
• ゆき　'snow'
• ひめ　'princess'
• しらゆきひめ 'Snow White'

If white is しろ, why is 'Snow White' not しろゆきひめ？

Answer 1

As @sawa posted with the link in the comment, sometimes words have exceptional readings when in compound form. 白（しろ） is the colour white, but in certain compound words it has the reading しら.

Exs:

しらゆき　→　pure white snow
しらさぎ　→　white heron
しらが　→　white (grey) hair