392 PROF. HUXLEY ON THE REPRESENTATIVES OF [May 27, 
the inner side of the surface of the os articulare.”’ (Stannius, ‘ Haad- 
buch d. Zootomie,’ Zweiter Theil. Amphibien, p. 58, 1856.) 
Prof. Peters adds to this account of the matter the following 
statements (Monatsberichte, 1869, pp. 593, 594) :— 
That Meckel’s cartilage, which persists throughout life in the 
Crocodile, becomes very slender posteriorly, and passes through the 
hole in the os articulare; that this slender cartilage then ascends 
upon the posterior and upper face of the quadrate bone enclosed in 
a membranous sheath; that, having reached the posterior edge of 
the membrana tympani, ‘‘it becomes connected with a cartilagimous 
plate, the narrow middle part of which is bent inwards towards the 
columella auris, with the external end of which it is connected by a 
joint. The broadest part of this cartilaginous plate is shaped like 
an axe-head, is directed perpendicularly against the membrana tym- 
pani, and forms, at the anterior end of its convex outer edge, a little 
plate which lies in the middle of the membrana tympani. It causes 
this region of the membrane to project slightly outwards, in the adult 
as well as in the young, and gives attachment to a filiform tendon 
which proceeds from the posterior boundary of the tympanic cavity. 
The other part of the cartilaginous plate bends away at an obtuse 
angle from the former, and has also the form of an axe-head, the 
convex edge of which, however, is narrower, and is applied below 
the posterior and inner part of the tympanic membrane to the carti- 
laginous margin of the tympanum.” Prof. Peters considers that the 
last mentioned triangular cartilage is the homologue of the ma/leus. 
In another embryo 203 centimetres long, Prof. Peters finds (/. e. 
p. 594) a “little, short, cylindrical, intermediate cartilage,’ which 
connects the columella {s/apes]| and this so-called malleus, and which 
he compares to the zaeus, or the os lenticulare. 
In a subsequent communication (7th January, 1869, Monats- 
berichte, pp. 6-8) “‘ On the cavities of the Lower Jaw in the Croco- 
dile,” Prof. Peters repeats the assertion that his so-called ‘ malleus ”’ 
is connected by a cartilaginous cord with the posterior end of Mec- 
kel’s cartilage, and states that he is unable to find the duct by 
which (as Stannius states) the pneumatic cavity of the os articulare 
is placed in communication with that of the quadrate bone. 
Nevertheless the description given by Stannius is perfectly correct, 
and I am puzzled to comprehend how the pneumatic duct, which 
places the air-cavities of the quadrate and articular bones in com- 
munication, can be confounded with a cartilagimous rod surrounded 
by a membranous sheath. The fact is that there is no direct con- 
nexion between the posterior part of Meckel’s cartilage and the so- 
called “ malleus ;”’ and thus, I cannot but think, the whole founda- 
tion of Prof. Peters’s argument collapses. 
Before particularly describing the very curious and instructive 
character of the outer extremity of the stapes (or so-called columella 
auris) and of the parts connected with it in the Crocodile according 
to my own observations, it is proper to remark that both Cuvier and 
Windischmann observed, though they did not quite rightly inter- 
pret, its structure. 
