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XX. On the Development of the Ossicula auditus in the Higher Mammalia. 
By Alex. Fraser, M.B., &c., The Owens College , Manchester. 
Communicated by Dr. Allen Thomson, F.R.S. 
Received March 16,—Read March 30, 1882. 
[Plates 54-58.] 
Contents. 
I. Intro duction... 
II. Historical... 
III. Personal work. 
1. Methods of preparation, and general statements . 
2. Description of the work— 
a. The parts in relation with the ossicnla auditus. 
1). The proximal extremities of the first two post-oral cartilages and a 
comparison between the embryonic and adult malleus and incus 
The embryonic and adult description of the stapes and the artery in 
relation with it . 
c. Summary and results....... 
3. References ... 
4. Explanation of the figures. 
Page, 
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INTRODUCTION. 
Since the discovery by Meckel of the cartilage which bears his name and the subse¬ 
quent discovery by Pathke of the cartilaginous rods immediately succeeding it, 
anatomists and embryologists have not failed to be intensely interested in the elucida¬ 
tion of their history. Htjschke was the first to limit the origin of the ossicula 
to the cartilages of the first two post-oral arches, but it is to Reichert that the first 
full and masterly description of these two cartilages is due. Looking at the wide¬ 
spread existence of these two rods in all classes of the Vertebrata, and the differentia¬ 
tion taking place at their proximal extremities, which may result either in the 
formation of a suspensory apparatus, or in one which, changing its function, is sub¬ 
ordinated to the organ of hearing, it can scarcely be wondered at that the opinions 
concerning the homology of the differentiated parts should be various and conflicting. 
Nor can it be otherwise, seeing that as yet there is no general agreement as to what 
