Two Indonesian Bone Calendars

probably Batak, Northern Sumatra, age unknown, top bone portion with incised salamander or lizard on one side and repeating symbols verso, drilled holes on the bottom edge tied to bamboo strips with incised symbols, 8-1/2 x 5-1/4 in.; with smaller plaque decorated with similar lizard form on one side and grid with symbols verso, 4-3/4 x 1-1/2 in.ÿ ÿ - Provenance: Private New England Collection
Condition Report: some yellow and brown patination to bone and bamboo strip, both with wear to incised decoration