412 



ANIMAL MECHANICS. 



I have had an opportunity of examining the following speci- 

 mens of this interesting group of Birds : — 



i°. Three Ostriches. 

 2°. Four Emus. 

 3°. TwoRheas. 

 4°. One Cassowary. 



In the Hip joint of the Struthionidaa, the following peculi- 

 arities are observable : — 



i°- The Agitator caudce and Tensor femoris vaginae form an 

 outer sheet of powerful muscles, which overlies the glutseal 

 muscles. 



2°. The Glutceus quartus muscle is always present, 



3°. The Iliacus muscle is also present. 



4°. The Adductor tertius (brevis) is invariably absent. 



5°. The Rectus femoris is present in the Ostrich and Rhea, 

 and has relation in these, as in other birds, to the Solo3us 

 muscle, and to the perforate flexors of the most important toe. 

 This muscle is totally wanting in the Emu and Cassowary. 



6°. The Biceps femoris acquires an extraordinary develope- 

 ment, intimately related to the unusual running power of this 

 remarkable group of birds. 



The following Table shows the muscular type of the 

 Ostrich : — 



