Mackintosh — On the Myology of the Genus Bradypus. 517 
But if U satisfy botli these conditions it is easily shown mathema- 
tically that 
Hence it is evident that the required equation of equilibrium is 
This law may be otherwise stated thus : — 
Let tty, a.^, be the quantities of hydrochloric acid combined with 
the quinia and brucia respectively. Then we know that Si, S2, are 
respectively equal to «i, a.^ multiplied by constant quantities. Hence, 
If to a mixture of quinia and hrucia there he added a quantity of hy- 
drochloric acid insufficient to convert the whole of hoth bases into salts, 
the products made by muUiplyiny the uncombined portion of each base 
with the portion of acid combined with the other base, have to each other 
a constant ratio. 
The author showed the bearing of this law upon the theory stated 
by Professor Williamson, that chemical combination is not statical, 
but dynamical, observing that this theory is quite in accordance with 
the result which he has obtained. It would be, on the other hand, 
difficult to reconcile the statical conception with this result, or even 
with the fact that there can be but one equation of equilibrium. 
XL VI. — On the Myology of the Genus Bradyfxjs. By H. W. 
Mackintosh, E. A. 
Through the kindness of Dr. Macalister, Professor of Comparative 
Anatomy and Zoology in the University of Dublin, I had the opportu- 
nity of being present during the dissection of a fine specimen of Arcto- 
pithecus Blainvillei, and on the notes of that examination, together with 
reference to the former dissections of Bradypus tridactylus by Professors 
Macalister^' and Hamphry,f the following paper has been compiled. 
Si ' S.2 
= const. 
or 
S1S2 = K JB^S^. 
[Eead November 10, 1873.] 
* Annals and Magazine of Natural History, July, 1869. 
t Journal of Anatomy and Physiology, 2nd series, No. 5, Nov. 18G9. 
