or THE SKULL IN THE UEODELOUS AMPHIBIA. 
559 
upwards and backward from the articular condyle ( q .) to the top of the front half of the 
otic process, that is its handle : the broad, lower part takes up much of the cartilage ; 
but higher up it is only a hard wall, with cartilage before and behind it. The otic 
process ends as a lobe behind, and the lower part of the suspensorium is subalate also. 
The condyle is well scooped ; its upper edge overlaps the lower. The chondro- 
pterygoid is a huge tongue, whose base extends from the hinge, externally, to the pedicle 
within ; it is narrow and terete in front, where it has gained the small postpalatine 
element, and the blunt point just reaches another cartilage, the antorbital ( a.o .). 
The small osseo palatine (pa.) is hatchet-shaped ; its blade is on the inside, and its 
handle behind ; this part just touches the “ osteo pterygoid ” (pg.), a large, triangular 
plate of bone, serving, like the one in front, as a splint to the underface of the quadrato- 
pterygoid arcade. 
The sinuous sides of the bone (figs. 2 & 4) only reveal a little of the cartilage below, 
which overlaps the bone within and behind ; the axes of the two bony plates are coincident. 
The suspensorium is tied to the cranium at a fourth place ; the stapes (figs. 2, 4, & 5, st.) 
is unusually solid and projecting, its outstanding process looking a little forward. From 
that process a ligament arises which spreads into a fan-like fascia, which is inserted 
along the under and outer edges of the suspensorium from the lobe of the otic process 
to the lobe of the quadrate. 
This fascia helps to form the rudimentary tegmen tympani ; it lies some height above 
the portio dura as it passes to the hyoid cornu and the mandible *. 
The mandible (Plate 25. figs. 4, 5, and Plate 26. fig. 5) is a large cartilaginous arch, 
with three bony plates wrapped over it. The dentary ( d .) is almost entirely external ; 
it reaches nearly to the angle ; the splenial ( sp .) not half so large, but, like the dentary, 
dentigerous, lies entirely on the inner side ; it occupies most of the anterior three fifths 
in extent. The articulare (ar.) forms a trough in which the thicker proximal part of 
the bar lies ; it is principally internal, and reaches nearly to the chin ; the thick longi- 
tudinal convex condyle rises out of the bone, and appears above it. The quadrate half 
* Professor Huxley pointed out this anomaly to me, showing me that this ligament cannot correspond to 
the “ suspensorio-stapedial ” ligament of Menobranckus (op. cit. p. 192). Until quite lately this enigma has 
remained unsolved ; I had found more or less ossified cartilages attached, either directly or hy ligament, to the 
stapes in certain North- American Newts ( DesmognaiJius fuscus , Spelerpes salmonea , and S. rubra ) ; hut until I 
dissected the Menopome they remained uninterpreted. 
In the latter type it is impossible to mistake the stem of the stapes (partly ossified where it joins that plate) 
for any thing else than a “ spiracular cartilage,” a structure so common in the Selachians (see Ge&enbaur). The 
spiracular cartilage is an offshoot from the top of the mandibular pier (=the hyoidean and branchial rays of the 
Selachians), and in the Erog is, during the larval stage, a part of the suspensorium ; in that type it becomes 
separated, and is specialized into the cartilaginous “ annulus tympanicus.” Professor Huxley, in his paper on 
Ceratodus (P. Z. S. 1876, p. 42), rightly compares the spiracular cartilage of Cestracion to the “ otic process ” of 
the Prog ; it does correspond to the permanent process in the metamorphosed Prog (see “ Prog’s Skull,” plates 
5-9, where the small mandibular ray, afterwards spiracular cartilage, then tympanic ring, is lettered sJi.m.). 
"W iedeesheim (‘Das Kopfskelet der Urodelen,’ plate 2. fig. 24) represents the facial nerve as passing over the 
stem of the stapes (op.) ; this is an error. I learn from him that the same part occurs in Cryptobranchus, 
Ellipsoglossa , and Banodon. 
