1228 CLASS AVES. 



the want of a bridge over the extensor tendons in the tibia ; and 

 the suppression of the hallux. The family DromcBidce is repre- 

 sented by the existing Emeu (Dromceus) of Australia, and also by 

 fossil species in the Pleistocene of the same country. Dromornis, 

 from the latter deposits, is an extinct genus referable to this family. 

 The characters of the pelvis of the existing genus are shown in fig. 

 1 107. The Casuariidce, now characteristic of the Australasian 

 region, have not hitherto been definitely recorded in a fossil state ; 

 although it is possible that a phalangeal from the Indian Siwaliks 

 may be referable to this family. 



Suborder 6. Rhe^e. — The Rheidce, which alone constitute this 

 group, and are confined to South America, differ from the Megi- 

 stanes by the structure of the palate, as well as by the longer hu- 

 merus, the presence of three digits (of which two are clawed) in the 

 manus, by the ventral union of the ischia, and the absence of an 

 aftershaft to the feathers. Remains of Rhea, which are referred to 

 the existing species, occur in the Pleistocene cave-deposits of Brazil. 



Suborder 7. Struthiones. — The family Struthionidtz is the 

 sole representative of this suborder ; the only existing species being 

 the Ostrich (Struthio camelus), which is now confined to Africa and 

 Arabia, although it formerly ranged into Persia, and probably also 

 to Baluchistan and the north-west frontier of India. In addition 

 to the characters of the palate, Struthio differs from Rhea by the 

 union of the pubes in a ventral symphysis, and also by the suppres- 

 sion of the second digit of the pes, in consequence of which the 

 distal end of the tarso-metatarsus has but two trochlese. This genus 

 is represented in the Pliocene Siwaliks of India, and also in the 

 Lower Pliocene of the Isle of Samos, in the Turkish archipelago, 

 by remains referred to two species. These forms, which may be 

 specifically the same, appear closely allied to the existing Ostrich. 

 An egg, from Tertiary beds near Gallipoli — the ancient Chersonese 

 — described under the name of St?-uthiolithus, probably belongs to 

 the existing genus, and very likely to the species occurring at Samos. 

 These fossil forms point to the conclusion that the original home of 

 the genus was probably in Asia. 



Suborder 8. Gastornithes. — The Gastornithidoe, whose re- 

 mains occur in the Lower Eocene of Europe, were large Birds 

 which may probably be classed with the Ratitae, and are apparently 

 entitled to distinct subordinal rank. Their tibia agrees with that of 

 the Apteryges and Immanes in having a bony bridge over the ex- 

 tensor tendons, but makes a curious approximation in shape to that 

 of certain members of the Carinate suborder Anseres. The wings 

 were somewhat larger than in the Ostrich ; and the cranium, which 

 is estimated to have been fifteen inches in length, had the alveolar 

 margins of the jaws serrated, as in the genus Odontopteryx (fig. 



