Another type exists in Rhea and in the Anseriformes, greatly specialized by being spirally twisted and partly reversible like the finger of a glove.
Order Anseriformes.-Desmognathous, nidifugous; with two pairs of sterno-tracheal muscles, with complete basipterygoid processes and with a penis.
Pelargomorphae = Ciconiiformes + Anseriformes + Falconiformes.
Anseriformes Podicipitiformes Pelargornithes.
Orders: Ichthyornes, Colymbiformes, Sphenisciformes, Procellariiformes, Ciconiiformes, (Suborders: Steganopodes, Ardeae, Ciconiae, Phoenicopteri), Anseriformes (Sub-orders: Palamedeae, Anseres), Falconiformes (Sub-orders: Cathartae, 1 Craniata may be usefully divided into 3 grades: (a) Branchiata Heterodactyla, which includes Pisces except Cyclostomes.