acrania
[ā-krā′nē-ə, ə-krā′-]
n.
Congenital absence of all or a part of the skull.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Examples from the Web for acrania
Historical Examples of acrania
Hence we may call it after the Acrania as well as after the Tangles.
The History of Creation, Vol. II (of 2)Ernst Haeckel
It is absent as a distinct gland in the Acrania and Cyclostomata.
The skull-less animal lancelet, which is still living, affords a faint idea of the members of this group (acrania).
Was Man Created?Henry A. Mott