(biology) Of or pertaining to something at its lowest point; designating the part opposite to the apex.
1946—Cushman, Joseph A. (1946). Upper Cretaceous Framinifera of the Gulf Coastal Region of the United States and Adjacent Areas. Professional Paper 206. Washington, D. C.: U. S. Department of the Interior, Geological Survey. p. 70 – via Google Books.
The deck, which is not far below the aperture, has a narrow indentation on the abapical side and a wider indentation on the adapical side.
1973—Henderson, R A (March 1973). "Clarence and Raukumara Series (Albian—?Santonian) Ammonoidea from New Zealand". Journal of the Royal Society of New Zealand 3 (1): 86. Retrieved 3 February 2016 – via Google Books.
The two abapical rows of tubercles of available specimens show a complete range of variation from completely separated to almost completely coalesced.
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