appendix/appendices ??

[mycatis]

Help, I'm writting a report and my mind has gone blank. Which one is the plural? appendix or appendices? any idea please folks? (I cant believe I cant think which way round it is!)

[BigMac]

appendix noun (plural: appendixes or appendices) 1 a section containing extra information, notes, etc at the end of a book or document.
Source: Chambers Reference Online