Dictionary.net

• A division of nudibranchiate Mollusca, in which the gills form a wreath or cluster upon the posterior part of the back. See Nudibranchiata, and Doris.

2010 - New Age Dictionary Database
By Oddity Software

• A division of nudibranchiate Mollusca, in which the gills form a wreath or cluster upon the posterior part of the back. See Nudibranchiata, and Doris.

1913 - Webster's Revised Unabridged Dictionary
By Noah Webster.