1869.| ON THE MALLEUS AND THE INCUS OF THE MAMMALIA. 391 
6. On the Representatives of the Malleus and the Incus of 
the Mammalia in the other Vertebrata. By T. H. 
Houxtry, F.R.S. 
In the course of the last two years, Professor Peters has contributed 
to the ‘ Monatsberichte’ of the Berlin Academy a series of papers 
in which he advocates what I may term, for brevity’s sake, the ‘‘ Oke- 
nian ”’ doctrine of the homologies of the ossicula auditis of Mammals 
and of the quadrate bone of the other Vertebrata. According to 
this view, the osstewla auditis of Mammalia are completely repre- 
sented by the auditory columella in other Vertebrata, while the 
tympanic is the homologue of the quadrate bone. In supporting 
it, Professor Peters necessarily argues against the doctrine originally 
put forward by Reichert, and subsequently adopted by myself, that 
the auditory columella of the lower Vertebrata does not answer to 
all the ossicula audités of the Mammalia, but only to the stapes—the 
incus being represented by the quadrate bone, the malleus by the 
articular ; while the homologue of the tympanic is only to be found 
occasionally, in ossifications of the fibrous frame of the tympanic mem- 
brane. 
In the first two papers of the series, Prof. Peters bases his argu- 
mentation upon the anatomical relations of the lower jaw and the 
tympanic bone in the Marsupialia and Monotremata ; but as these 
facts are, undoubtedly, capable of being interpreted as well upon the 
Reichertian as upon the Okenian hypothesis, I did not conceive it 
necessary to enter, at present, upon any discussion of them. 
On the 19th November, 1868, however, Prof. Peters made a third 
communication to the Berlin Academy, “ Upon the Auditory Ossicles 
aud the Meckelian Cartilage in Crocodiles,” which was followed on 
the 7th January, 1869, by a fourth, “ Upon the Auditory Ossicles of 
Chelonia, Lizards, and Ophidia, as well as upon the cavities of the 
Lower Jaw of the Crocodile,’ which seemed to me to demand imme- 
diate attention ; for the quadrate bone of the Crocodile cannot pos-, 
sibly represent either the incus, or the malleus, if the statement of 
anatomical facts made by Prof. Peters is correct. 
I therefore proceeded to the verification of his descriptions with 
much interest and a little anxiety ; but after dissecting the skulls of 
several young Crocodiles with great care, I must declare my convic- 
tion that Prof. Peters is in error as to the facts, and, therefore, that 
the argument he bases upon them falls to the ground. 
The able anatomist Stannius first drew attention to the pnenma- 
ticity of the lower jaw in the Crocodile, in the following terms :— 
“The os articulare of the lower jaw is distinguished by its pneu- 
maticity ; its great hollow cells communicate, by a canal which lies 
at the back of the os tympanicum [quadratum ], with the air-chambers 
of the cranial bones. The lowest part of the canal in question forms 
a groove in the dry skull. This, in the fresh skull, is converted into 
a soft tube ; and a free membranous tube leads into a hole placed on 
