1869.] THE MALLEUS AND THE INCUS OF THE MAMMALIA. — 393 
Cuvier (Ossemens Fossiles, ix. p. 177) states of the stapes of the 
Crocodile, that “it consists of a long narrow elliptical plate, attached 
to the fenestra ovalis, from which passes a long and slender stem, 
which goes, becoming a little softer, to attach itself to the tympanic 
membrane ; it then bends back and follows it, being fixedly attached 
thereto and taking a cartilaginous consistency, as far as its posterior 
margin. From the posterior wall of the tympanum a muscular fila- 
ment. proceeds and becomes attached to the stem of the bone at 
about a third of its length [from the tympanic membrane]; anda fold 
of the internal lining of the tympanum forms a triangular ligament 
which extends to the same point, and thus contributes to fix the stem 
to its recurved and tympanic portion.” 
Windischmann observes, “‘Ossiculum auditorium Scarpa delineavit, 
fere quatuor lineas longum, opereulo triangulari instructum. In 
altera extremitate in cartilaginem tripartitam desinit, cujus una pars, 
ut dixi, in membrana media tympani adhezeret, alize duz in falce 
membranam hancce excipiunt.’”’ (Windischmann, De penitiori auris 
in Amphibiis structura. 1831.) 
The “triangular ligament’ of Cuvier is clearly the “ malleus” of 
Prof. Peters; and the same part seems to be meant by the “aliz 
due’ of Windischmann. 
What Cuvier terms the “stem”’ of the stapes of the Crocodile is 
more or less completely ossified ; but I find, in all cases, that it passes 
directly into the cartilaginous axehead-like plate, the convex edge 
of which is connected with the membrana tympani. There is no 
trace of the joint described by Prof. Peters in any of the specimens 
I have examined ; neither have I been able to see anything of the 
‘filiform tendon ’’ which is said to “proceed from the posterior 
boundary of the tympanic cavity.” 
Where the outer end of the stem of the stapes widens out into 
this process for the tympanic membrane, which I shall call the 
“ extrastapedial”’ cartilage (fig. 1, #.S¢), it gives off, upwards 
and backwards, a slender cartilaginous prolongation, which expands 
and becomes the second ‘“ axehead-like”’ process, called “‘ malleus ”’ 
by Prof. Peters (S.S¢); but I have not been able to detect any 
trace of what Prof. Peters calls ‘‘a little short cylindrical interme- 
diate cartilage’ between this and the stem of the stapes. In all 
the specimens I have examined there is complete cartilaginous con- 
tinuity between the two. 
What Prof. Peters terms the “‘ cartilaginous margin of the tym- 
panum”’ is a backward prolongation of the cartilage of the periotic 
region of the skull, which corresponds in part, if not wholly, with 
the tegmen tympani of a mammal. It may be called the ‘ parotic 
process” (fig. 1, Pe.c); and in the adult it is converted, in great 
measure, into a slender and curiously curved process of the pro-otic, 
and, in part, into a process of the so-called exoccipital bone. Mus- 
cular fibres, which represent the stapedius muscle (fig. 2, Stp), 
proceed from this cartilaginous margin, or the corresponding bones, 
to the margin and outer face of the cartilage called ‘malleus’? by 
Prof. Peters, but which I shall term the ‘ suprastapedial’’ carti- 
