Antler/bone comb with iron rivets

Bone comb, length 10.6cm, but ends broken. Constructed of flat bone plate with teeth cut only on one side after the plate has been mounted between curved backplates. These of semi-circular section, clamped together by 5 iron rivets. Decorated with cross-hatching in panel along back, and in panels at ends, and by 5 triple ring-and-dots between rivets, the middle 3 with larger ring outside. Teeth mostly broken but probably originally finished with curved edge. Cut by saw. Sketch in Diary shows back of comb originally terminated in projections at end to case in teeth. Possible? More probably middle plate left uncut at ends to form casing, and decorated to match ends. Decoration on both sides, the same. Bone very worn and abraded.Original label: Kingston 1773, 299 written on back.