aptychus

aptychus is defined in Webster's Unabridged Dictionary (1913) with 1 sense. The full text of each entry is reproduced verbatim below.

Definitions

  1. 1.A shelly plate found in the terminal chambers of ammonite shells. Some authors consider them to be jaws; others, opercula.

Source: Webster's Unabridged Dictionary, 1913 edition (public domain, via GCIDE / Project Gutenberg).

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