The Oxford Companion gives it as "from four to nine strings (usually five or six)".

"Chanterelle" is, I gather, the general term for teh highest sounding string in other instruments too, such as the violin.

It could be that the OCM got it's info from that 1911 encyclopedia - but the fact that both refer to the fifth string as "the melody string" set me wondering whether in fact it might sometimes have been used that way, with the rest of the strings in an open D, while playing the tune on the fifth. Sort of reverse to the way it's normally done.