Reduction of the number of toes (the fifth shows no traces whatever, not even in Archaeopteryx) begins with the hallux, which is completely or partly absent in many birds; the second toe is absent in Struthio only.
In the ostrich, Struthio, the craze of overloading the stomach with pebbles which, when triturated into sand, are not voided, has brought about a dislocation, so that the enormously widened and stretched space between proventriculus and gizzard forms a bag, directed downwards, whilst the gizzard itself with part of the duodenum is rotated round its axis to more than loo°.
Ostriches, undistinguishable from Struthio, have been found in Samos and in the Sivalik Hills.
From Samos a large stork, Amphipelargus, and a typical Struthio; from the Sivalik Hills on the southern flanks of the Himalayas also an ostrich, and another Ratite with three toes, Hypselornis, as well as Leptoptilus, Pelecanus and Phalacrocorax.
All the existing Ratitae (with the exception of the ostriches of Africa and South America, belonging to the genera Struthio and Rhea, and comprising at most but five species) are found in Austrogaea and nowhere else.
Struthio in Africa and Arabia, fossil also in the Sivalik Hills, and Aepyornithidae in Madagascar; Pittzdae, Bucerotinae and Upupinae, of which Upupa itself in India, Madagascar and Africa; Coraciidae; Pycnonotidae or bulbuls; Trogonidae, of which the Asiatic genera are the less specialized in opposition to the Neotropical forms; Vulturidae; Leptoptilus, Anastomus and Ciconia among the storks; Pteroclidae; Treroninae among pigeons.
Between fifty and sixty so-called families of land birds alone are found within its limits, and of them at least nine are peculiar; the typical genera of which are Buphaga, Euryceros, Philepitta, Musophaga, Irrisor, Leptosoma, Colius, Serpentarius, Struthio, Aepyornis.
Struthio, ostrich, Pliocene of Samos and of north-west India, now Africa and Arabia.
Instead of recognizing, as before, a subclass in the Ratitae of Merrem, Nitzsch now reduced them to the rank of an order under the name " Platysternae," placing them between the " Gallinaceae " and " Grallae," though admitting that in their pterylosis they differ from all other birds, in ways that he is at great pains to describe, in each of the four genera examined by him - Struthio, Rhea, Dromaeus and Casuarius.
A diagnosis covering all the Ratitae (struthio, rhea, casuarius, dromaeus, apteryx and the allied fossils dinornis and aepyornis) would be as follows - (i) terrestrial birds without keel to the sternum, absolutely flightless; (ii) quadrate bone with a single proximal articulating knob; (iii) coracoid and scapula fused together and forming an open angle; (iv) normally without a pygostyle; (v) with an incisura ischiadica; (vi) rhamphotheca compound; (vii) without apteria or bare spaces in the plumage; (viii) with a complete copulatory organ, moved by skeletal muscles.
Struthio alone still stands aloof, possibly because it is the oldest and most specialized form.
Avis struthio; Gr.
Crrpov0LWV or o .47as a-rpov06s); the Struthio camelus of Linnaeus, and the largest of living birds, an adult male standing nearly 8 ft.
Wolf, of the male Struthio camelus; J.