Acrania
Pronunciation : A*cra"ni*a
Part of Speech : n.
Etymology : [NL., from Gr.
Definition : 1. (Physiol.)
Defn: Partial or total absence of the skull.
2. pl. (Zo?l.)
Defn: The lowest group of Vertebrata, including the amphioxus, in which no skull exists.
Source : Webster's Unabridged Dictionary, 1913