Nummulites (English spelling)

Japanese: ヌンムライト（英語表記）Nummulites

A genus of large foraminifera that appeared in the Paleocene of the Tertiary Period and became extinct in the Oligocene. It is also called nummulite, as its scientific name (Latin nummus means money) was derived from its external shape. The shell of nummulite has a convex lens or disk shape, and following the initial chamber, many chambers are arranged in a flat plane, tightly coiled in a spiral shape. Only the last chamber is visible on the outer surface (enveloplasty). The sutures, which are the intersections between the septa that separate the chambers and both sides of the shell wall, are thin and thread-like, so they are called septum filaments.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

大型の有孔虫の一つの属で，第三紀暁新世に出現し，漸新世に絶滅した。外形にもとづいて名づけられた学名(ラテン語nummusは貨幣)の意味するとおり貨幣石とも呼ばれる。ヌンムライトの殻の外形は凸レンズないし円盤形を呈し，初室に続いて多数の室がらせん状に密に巻きながら，平面的に配列する。外面には最後の一巻きの室のみが現れる(包旋回)。各室を仕切る隔壁と殻壁両側面との交わりである縫合線は細い糸状になるので，隔壁フィラメントと呼ばれる。

出典　株式会社平凡社世界大百科事典第２版について　情報

<<: Ney, Michel

>>: al-Nuwayri (English spelling)