STRUTHIONID^ STEUTHIO 523 



Sub-Class II. RATIT^. 



This Sub-class includes a number of flightless birds without any 

 keel to the sternum ; all have small wings and no stiff contour 

 feathers. Other characters are : skull dromseognathous {of. vol. iii, 

 fig. 7, p. 7), holorhinal, and with basipterygoid processes ; coracoid 

 and scapula fused and forming a wide angle with each other ; oil 

 gland absent ; caeca very long ; accessory femoro-caudal, semitendi- 

 nosus and accessory semitendinosus always present, the first-named 

 provided with an additional slip. 



The existing members of the Sub-class are separated iuto three 

 or four Orders and five Families, comprising the Ostriches, Eheas, 

 Emus, Cassowaries and Kiwis ; all of which are confined to the 

 Neotropical, Ethiopian and Australian regions at the present time, 

 though fossil remains of some of the groups have been found in 

 other parts of the world. 



Order XXI. STRUTHIONES. 



Family I. STRUTHIONID^. 



Only two toes, the third and fourth, present ; the terminal 

 phalanges shortened, provided with nails ; no aftershaft to the 

 feathers ; all five Garrodian thigh-muscles present ; no clavicles ; 

 caeca long ; rectrices large. 



This Family contains only the single genus here described. 



Genus I. STRUTHIO. 



Type. 

 Struthio, Linn. Syst. Nat. 12th ed. i, p. 265 (1766) ... S. camelus. 



Bill broad and depressed, the culmen flattened and the tip 

 strong, rounded and overlapping the lower mandible ; nostrils oval, 



