426 MR. P. H. GOSSE ON THE STRUCTURE, FUNCTIONS, AND HOMOLOGIES 
a powerful joint, which seems to be ginglymate in its character, admitting of motion 
in one plane only. The two opposing surfaces appear to be united by elastic liga- 
ments, while their irregularities lock into each other. 
26. The inferior portion of the malleus, which I shall call the manubrium (c), is an 
irregularly-curved piece, shaped somewhat like the scapula of a mammal, knobbed 
at its head, and flattened at its lower or free end, where also it is twisted to one side. 
Ridges run down it, on both the interior and exterior surfaces. The head is obliquely 
truncate ; and it is this oblique surface {d), that is jointed to the superior portion (e), 
which, from its prevalent form in other genera, rather than in this, I call the uncus. 
27 . The uncus, when at rest, is placed nearly at right angles to the manubrium, 
but is capable of considerable change of relative position by means of the joint. It 
consists of five or six Jinger-like processes (figs. 2, 3), set parallel to each other, and 
separated by narrow interspaces, which appear to be occupied by a thin membrane. 
These are not joints, moveable inter se, but resemble the teeth of a comb in their 
mode of origination. They are slender, rough, and enlarged at their tips ; and the 
ultimate one of the series, next the dorsal side (fig. 3), is an offshoot from the penul- 
timate. Their extremities are bent abruptly downward, approaching each other ; 
and they are so arranged, that the whole uncus forms a segment, about one-third, of 
a cylinder, or a drum with incurving sides, with a broad truncate end (fig. 4). 
28. The incus {/) also consists of distinct articulated portions. The principal are 
two stout rami (g), together vase-like in ventral aspect (fig. 1), resting on what 
appears to be a slender pedicel {fulcrum, h). But viewed laterally, the fulcrum is 
seen to be a thin plate (fig. 5), to one edge of which the rami are jointed, in such a 
manner, that they can open and close, like a pair of shears. Each ramus is a thick, 
somewhat trigonal piece, with the outer side rounded, the upper side hollowed, and 
the inner side flat, and in contact with the corresponding face of its fellow, in a 
state of repose. The uncus of each malleus, respectively, falls into the concavity of 
each ramus ; and is fastened to it by a stout triangular muscle {i), which is seen 
passing from the hollow of the ramus to the under surface of the uncus. 
29. Such are the firm parts ; which, whatever their material, have great strength, 
solidity, and density. Their density, however, is not uniform ; for, in some parts, 
they appear to merge insensibly into membrane, or into the muscular bands. They 
are perfectly transparent and colourless, and have a high refractive power. Their 
substance is not affected by a solution of potash, but is instantly dissolved, without 
effervescence, by hydrochloric, nitric, and acetic acid. Sulphuric acid also dissolves 
it, without any ebullition that appears to originate from the contact. 
30. The special muscles which move these organs are numerous, and several of 
them massive. The walls of the mastax themselves are, as has been already said, 
muscular, and so thick as to leave the internal cavity but small. There are indica- 
tions of muscles, which I have not been able satisfactorily to define ; but the following 
are well made out. A thick muscle (/) embraces the upper and outer angle of the 
