kame no o 亀の尾

Lit. tortoise tail. Short, diagonally set ribs with thin wooden strips called jaboko 蛇骨子 or koebi 小海老, forming a diagonal transition between the ceiling plates *mawaribuchi 回縁 atop a coffered ceiling's non-penetrating tie beams *tenjō nageshi 天井長押, and the frame *gōbuchi 格縁. These form an important component of a coved and coffered ceiling *oriage gōtenjō 折上格天井. The corner ribs sumikame no o 隅亀の尾, although the same height as other ribs have a different degree of curve. Ribs not set in corners are called hirakame no o 平亀の尾.