1869.] THE MALLEUS AND THE INCUS OF THE MAMMALIA. = 395 
which is continuous with the sheath of connective tissue which en- 
velopes the cartilaginous rod in question. It is this relation of the 
parts which, I am disposed to imagine, has deceived Prof. Peters, who 
seems to have taken the pneumatic duct and this cartilage for one 
continuous cartilaginous rod. In front, this minute cartilaginous style 
is in relation, as I have said, with the quadrate bone; behind, the 
portio-dura nerve passes down close to and parallel with it, and 
the digastric muscle covers it; above, it abuts against the lower 
and posterior walls of the tympanic cavity. Can there be any doubt, 
therefore, that it answers to the styloid cartilage, or proximal end 
of the hyoidean arch, in a mammal? 
A fold of the lining membrane of the tympanum (a, fig. 2) 
somewhat obscures the junction of the extrastapedial and suprasta- 
pedial cartilages with the styloid cartilage; but by detaching the parts 
and saturating them with glycerine and caustic soda, it is plainly 
demonstrable that the styloid cartilage is only connected by fibrous 
tissue, and, indirectly, by the stapedius, with the stapes. 
Fig. 2. 
Inner view of the tympanic membrane (7ym) of a young Crocodilus bipor- 
catus, with the attached stapedial cartilages (S.S¢, H.S7), the fold (a), 
the styloid cartilage (S¢h), and the stapedius muscle (S¢p). The stem of 
the stapes is cut through just where it begins to ossify. 
Thus, then, in the Crocodile, the connexion between the articulare 
and the stapes, supposed by Prof. Peters, does not exist ; but there is 
a very close connexion between the sfapes and a cartilage which 
distinctly represents the upper extremity of the hyoidean arch ; and, 
so far from the Crocodile furnishing any ground for the supposition 
that the stapes and its appendages are modifications of the skeleton 
of the first visceral arch, as is suggested by Prof. Peters, the facts 
observed strongly suggest that these parts are modifications of the 
skeleton of the second visceral arch. 
This suggestion is converted into a certainty when that remark- 
able Lizard Sphenodon punctatum (=Hatteria) is examined. Dr. 
