428 



ANIMAL MECHANICS. 



other in a manner that shows a wide variation from the type 

 of ordinary wings. This will appear better by arranging the 

 muscles, as before, into groups. 



Muscular Type of Wings of Ostrich and Rhea. 





Scapular. 



Abductor. 



Flexor. 



Extensor. 



Adductor. 





Per cent. 



Per cent. 



Per cent. 



Per cent. 



Per cent. 



Ostrich, No. i, . . . 



7.36 



53-49 



20.49 



5-24 



13.42 



Ostrich, No. 2, . . . 



7.74 



52.72 



19.28 



6. 10 



14. 16 



Rhea, No. 1, ... 



6.99 



44.10 



23.58 



6-55 



18.78 



Rhea, No. 2, . . . 



8-53 



45-5Q 



21.09 



8.06 



16.82 



Rhea, No. 3, . . . 



7.6l 



50.46 



I3.I6 



8.64 



20.13 



On comparing this Table with that already given for com- 

 mon birds, we find the columns of abductor and adductor 

 muscles precisely reversed : so that it may be asserted that 

 the wings of the Ostrich and Rhea are constructed on a type 

 the very opposite of that of the wings of common birds. The 

 wings recorded in the preceding Table are utterly incapable 

 of being used in flight, and it is extremely difficult to under- 

 stand how they could possibly represent common wings altered 

 from want of use, and so undeveloped. 



This argument becomes stronger from an examination of 

 the wings of the Emu and Cassowary, which are formed on a 

 type quite different from that of the Ostrich and Rhea, and 

 equally irreconcileable with the type of ordinary wings. This 

 is shown in the following Table : — 



