406 
MR. W. K. PARKER ON THE STRUCTURE AND DEVELOPMENT 
The suspensorium is now, in the closed mouth, placed at less than a right angle to 
the “ ramus besides this, it is now firmly attached by its upper edge to the outer face 
of the hinder half of the long sub-falicform squamosal (fig. 7, q., sq.). 
Inside the middle of the squamosal there is a small sub-oval scale of bone, the supra- 
teinporal : here it is only distinct for a time, but in Lizards it is so permanently. 
The quadrate (q.) is flat and fan -shaped above, and terete below : the upper part is 
still soft : the lower end only at the condyle. 
The articulare (ar.) has almost ossified the whole of the long angular process, and 
runs forward over the middle of the Meckelian rod (mb). 
At the middle and from thence, forward, that rod is wholly unossified, and in this 
type the middle of the mandible is its “coronoid region;” there the coronoid bone 
meets the splenial (cr., .sp.) ; they are attached by enlarged ends, the point of one 
looking forwards, and of the other backwards. 
The dentary (d.), surangular ( s.ag .), and angular (ag. ) are seen in the same figure : 
the latter on the inside mainly ; the other two principally on the outside. 
But the backward extension of the huge mandibular arch has thrust it past the 
hyoid rudiment ; this is the cause of the very peculiar position of the stylo-hyal and 
columella ( st.h ., co.) on the inner face of the quadrate. 
The third branch of the 5th nerve, the facial nerve, and the columella, take the same 
backward direction, as a correlate of the extreme backward extension of the gape. 
Notwithstanding the small size of the arrested hyoid arch, it has become segmented 
into the two normal pieces ; the columella (minus the stapedial plate) answering to 
the hyo-mandibular, whilst the stylo-hyal is the upper part of the familiar “ stylo- 
ceratohyal ” bar. 
The true stapedial portion of this compound columella (figs. 4, 5, 7, 8, st.) has its 
posterior margin almost straight, the fore edge being well curved : its inner face is 
concave (fig. 8). 
The shaft (co.) is gently sigmoid ; the terminal third is unossified : this is the 
“ extra-stapedial part,” and it has no supra-stapedial spur. 
The form of the original rod (Plate 28) is scarcely changed, but the direction is 
backwards instead of forwards ; the capitular part is below and forwards, the tuber- 
cular above and backwards. 
There is no distinct membrana nor cavum tympani, and at present the stylo-hyal 
cleaves to the columella. 
This element is reniform (fig. 8, st.h.), and its middle and convex portion is covered 
with a scabrous ectosteal plate ; this and the extra-stapedial are jammed between the 
skull and the quadrate (figs. 4 and 7) A 
* This explains what for many years was an enigma to me — namely, that in every ojjhidian skull I 
examined there was to he seen a thin scale of bone adherent to or coalesced with the inside of the 
quadrate, above its middle. The arrested stylo-hyal is stowed away there, permanently ; faint, and 
functionless. 
