Family XLIV. ALCINAE. AUKS.
Bill not longer than the head, much compressed, generally very high, in the species approaching the next family rather slender. Nostrils small, linear, basal, and sub-marginal. Head large, broadly ovate, anteriorly narrowed; neck short and thick; body full, compact, ovate, or somewhat elongated. Feet short, rather stout, placed far behind; tibia bare for a short space; tarsus very short, compressed, anteriorly scutellate; toes three, of moderate length, scutellate, webbed. Claws strong, arched, acute. Plumage dense, blended, soft. Wings small, narrow, pointed. Tail very short. Tongue slender, trigonal; oesophagus very wide, within the thorax extremely dilated; stomach rather large, muscular, with the epithelium dense and longitudinally rugous; intestine long and wide; coeca of moderate size. Trachea simple, with a single pair of inferior laryngeal muscles. Egg generally single.