B. Notochord with no vermiform process; pericardium simple; ventral part of pharynx large, and sometimes more or less separated from the branchial part (Fig. 4).
(a) Liver-sacs,[[26]] synapticula and nerve-roots present. .......... Ptychoderidae
(i.) Genital wings well developed.
(α) Gill-sacs opening by long slits. .......... Ptychodera, Eschsch.
(β) Gill-sacs opening by small pores. .......... Balanoglossus, Delle Chiaje.
(ii.) Genital wings hardly developed. .......... Glossobalanus, Speng.
(b) Liver-sacs, synapticula and nerve-roots absent. .......... Harrimaniidae
(i.) Proboscis long; one proboscis-pore. .......... Dolichoglossus, Speng.
(ii.) Proboscis short; two proboscis-pores.
(α) Two pairs of genital wings. .......... Stereobalanus canadensis, Speng.