410 HARRIS HAWTHORNE WILDER ON 
otic capsule. It is difficult to determine, in a piece of this shape, the location of the proc- 
esses cited by authors in their description of the quadrate of other Amphibia. The pos- 
terior lateral extension which runs along the side of the bone is probably the otic process, 
and the narrowed part, or its posterior prolongation, the pedicel. Of the two processes 
which form the isthmus and become applied to the trabecula, the anterior one may possi- 
bly be the ascending process. A slight angle seen in the anterior margin is doubtless the 
rudiment of the “ cartilaginous pterygoid” found in most Urodeles, the extension of which 
to the antorbital process would form the palato-pterygoid arch which is wanting here. 
Aside from its attachment to the trabecula, the quadrate, osseous and cartilaginous, enters 
into more or less complete attachment to four bones. As described above, two processes 
of the pro-otic form quite definite articulations with the quadrate cartilage, the ventral 
one receiving an articular surface formed by a thickened piece of cartilage in the middle 
of the posterior margin, and the dorsal one being applied along the inner edge of the otic 
process. The paraquadrate overlaps it externally, and the outer posterior corner of the 
palato-pterygoid fits into a groove in the inner side of the articular process and overlaps a 
raised area of the quadrate cartilage. The cartilaginous articulare of the mandible forms 
a movable articulation with it. 
In determining the position of an isolated osseous quadrate it may be remembered 
that the side showing the hollow groove is 
internal, that the larger end is anterior, and 
that the broader, plainer surface is dorsal. 
5 and 6. PARAQUADRATUM AND OPERCU- 
LuM. ‘These elements, of which the first is a 
5 
5 
x 
r 
° 
cc 
‘ 
S 
dermal bone, and the second an ossification 
= = 
aS 5 
. ys : : 
ie ay re os of a detached portion of the otic capsule, are 
eMcular procecs 
se termsetesne Pore ee ae closely connected topographically and joined 
to one another by | strong ligament which 
_-- Colawellar ---...... # . 
aaa Process of 
Opercutum 
unites processes in each bone mutually 
directed toward the other. The paraquadra- 
tum, the shape of which suggested a boom- 
erang to Huxley, attached in its normal man- 
ner to the little discoidal operculum, presents 
the appearance given in figure 11. When in 
INTERNAL place upon the skull, the paraquadrate lies 
along the outer side of the otic region, form- 
EXTERNAL. 
Fig.11. Right paraquadratum and operculum. ; 
Two views. X 3. ing the two sides of the pentagonal outline 
of the skull designated above as “ paraquad- 
