426 



ANIMAL MECHANICS. 



The relations among the types of these animals may be 

 seen from the following Table, in which the muscles are 

 arranged in groups, as before : — 



Muscular Types of Flying and Swimming Animals. 





Scapular. 



Abductor. 



Flexor. 



Extensor. 



Adductor. 







Per cent. 



Per cent. 



Per cent. 



Per cent. 



Per cent. 





Pteropus edulis, . . 



18.76 



18.16 



12.98 



11.78 



38.32 



2. 



Epomophorus Whitii, 



22. 14 



14.29 



13-57 



9.28 



40.72 



3- 



Green Turtle, . . 



3-4° 



16. 30 



16. 92 



5.67 



57. 7 1 



4- 



Hawk's- Bill Turtle, 



6.48 



2I.81 



7-15 



13.37 



5 I - I 9 



5- 



Logger- Head Turtle, 



8.78 



18.60 



20.06 



9. 14 



43-42 



6. 



Alligator, .... 



23.90 



14.52 



16.80 



4.71 



40.07 



7- 





36.33 



1 1 . 00 



18.70 



2.94 



31-03 



8. 



Seal, 



33.57 



I0.75 



23. 66 



1.68 



30-34 



The muscular types of these various animals are, of 

 course, very diverse ; but they all agree in the development 

 of the adductor muscles used in flying or swimming ; and 

 no other animals, except birds, present an approach to this 

 type. 



I shall conclude this section on muscular types by a few 

 observations on the "undeveloped" fore-limbs of the Stru- 

 thionidse, as I believe that a profound study of the muscular 

 types of these limbs leads us up to the conclusion, that they 

 could never have been intended for wings at all, but are pre- 

 pared for uses quite distinct from flying. 



As the question is one of some theoretical interest, I shall 

 use all the materials at my disposal, and allow my readers to 

 draw their own conclusions from a consideration of all the 

 facts I am able to lay before them. 



As it is a well known, although unexplained fact, that the 

 Ostrich and Rhea form a natural group on the one hand, con- 

 trasted with the Emu and Cassowary on the other,* I shall 

 discuss the muscular types of their wings separately. 



* Among muscular peculiarities not noticed by previous anatomists, I may 

 mention that in the Ostrich and fthea, the Obturator internus muscle is single, 



