This paper deals with the pedunculate cirripedes of the sessile famy Verrucidae only. All species represented in the National Museum are mentioned or described, and incidentally all known species of the United States and adjacent waters are treated monographically, though descriptive matter relating to well-known forms is restricted to keys for the determination of species.
This work is a continuation of the author's report on the Cirripedia contained in the United States National Museum, of which the portion relating to pedunculate forms was published in 1907. It was at first intended to record the species of sessile Cirripedia in the Museum, with their localities, and to describe and figure new forms. As the collection was worked over, its wealth in American barnacles became apparent and contains nealy every known species of the Western Hemisphere, many of which show variations special to American waters, altering the scope of this work which may now be described as a monograph of American sessile barnacles.