ON CERTAIN MUSCLES OF BIRDS. 187 
in the same family. As Mr. Sclater has shown, Podargus has no oil- 
gland, that organ being very small in the Caprimulgide generally, but 
large in Steatornis. 
If the absence of the ambiens muscle in the Strigide has the sig- 
nificance which I put on it, and is sufficient justification, in conjunc- Page 535. 
tion with other differences, for the entire separation of this family 
from the other Accipitres, then the above mentioned group of families 
seems a natural one;* but if the Strigide are intimately related to 
the Falconide and Vulturide, it is so difficult to believe that the 
Coraciidee and their allies are related to the Falconide, that the 
entire separation of the Strigide from the Caprimulgide seems 
essential, in which case the position of Steaternis becomes more 
doubtful. 
32. ON CERTAIN MUSCLES OF THE THIGH OF BIRDS, Page 626. 
AND ON THEIR VALUE IN CLASSIFICATION. 
(PL. ¥ : 
Part I+ 
In their works on the general anatomy of the animal kingdom Meckel 
and Cuvier have devoted special chapters to the myology of birds. 
The dissections on which their observations were based were evidently 
undertaken more with the desire to determine the relations borne by 
the muscles of birds to those of Mammalia and- Reptiles, than with 
the object of studying the variations in the arrangement of the muscles 
_ in the class itself. Nitzsch, Reid, Owen, Milne-Edwards, Coues, 
Selenka, and others have published their dissections of certain birds, 
as the Vulture, Penguin, Apteryx, Eagle, and Loon; and most of these 
are, from their accuracy and clearness, valuable additions to zoological 
knowledge. Sundevall seems to be the only ornithologist who has 
employed the variations that he has observed to be constant in 
different birds towards the furtherance of classification; and my 
results, on the D sence: discussed by him, in most cases correspond 
with his. 
The great opportunities afforded me by this Society for the study 
of a great many species of birds in the flesh, have reduced the diffi- 
* Prof. Newton has for.some time believed the Steatornithide and Caprimulgide 
. to be distinct families (¢f. Zool. Rec. vi. p. 67). 
+ Part IL. “ Proceedings of the Zoological Society,’ 1873, pp. 626-44. Read, 
June 17, 1873. 
