454 
MR. W. K. PARKER OK THE DEVELOPMENT 
the development of this particular skull, but also in the order of the types ; in the 
Amphibia, Reptiles, Birds, and Mammals these processes are seldom absent. 
The dorsal end of the suspensorium or mandibular pier has already become oblique ; 
the true extremity is now lateral, and is the pedicle of the pier ; this is an oblong 
tract or facet articulating with the basi-pterygoid face on the basal band. 
The second part is the otic process (behind pel.) ; it is a subtriangular “ ear ” of 
cartilage, running backwards towards the pier of the hyoid arch (hm.), under the 
superorbital rudiment (s.ob.). Thence the suspensorium narrows gently, and a little 
behind the middle of the bar forms, on its outside, a jutting step ; this is the gently 
concave quadrate hinge which articulates with the mandible ( mk .). 
The rest of the suspensorium lessens to one-half its hinder width, and is /-shaped, 
bending inwards at first and then outwards before it makes its last inward bend to 
join the trabecula (Plate 30, figs. 7, 8, p.pg ., tr j). The extent of the coalesced part is 
greater than the width of the bar; both that part and the fore part of the free bar 
belong, not to the proper pier of the mandible, but to the palato-maxillary arcade—it 
is the proper “ ethmo-palatine.” In the Tadpole of all, and the adult of most, 
Batrachia, it is not differentiated from the pterygoid band. The mandible (mk.) has 
already a flattish articular facet, an angular and a coronoid process; the main bar is 
gently arcuate, and lessens gradually to its distal end, which is rounded, and does 
not touch its fellow of the opposite side. 
The hyoid arch is large and highly subdivided ; it has now a large forwardly- 
projecting basal piece (Plate 30, fig. 8, b.hy.). 
The pier is the hyomandibular (hm.), with its styloid symplectic fore-growth (sy.) ; 
this part is free, and not, like its serial homologue the pterygoid process of the 
suspensorium, concrescent with the bar in front of it. This hyoid pier is still three- 
fourtlis as large as the pier of the mandible; its dorsal condyle is large and rounded, 
its body is swollen behind, ready to form the “ opercular process,” and below this knob, 
on the inner side, it is scooped for articulation with the inter-hyal (i.hy.). Here, 
as in the hyostylic types of fishes, the hyoid arch is subdivided primarily into an 
antero-superior and a postero-inferior bar; but in this type, as in the Teleostei, the 
latter is subdivided again into three segments—the inter-hyal, the cerato-hyal, and the 
hypo-hyal (i.hy., c.hy., h.hy.).* 
The inter-hyal (i.hy.) is a small, short, but thickish segment which articulates with 
the inner face of the hyomandibular (hm.) above, and with the cerato-hyal (c.hy.) 
below. The cerato-hyal is nearly as long as the mandible, and is twice as thick as its 
distal part; it is oval in section, rather pinched in at the middle, and rounded at both 
ends. The lower convex end fits into the shallow cavity on the top of the hypo-hyal 
* In the Sturgeon and its congeners the symplectic is segmented off from the hyomandibular, and the 
same thing often occurs in the diminished and modified hyoid pier of the Batrachia, and even amongst 
some of the Sauropsida, as in the Chelonia (see ‘ On the Skull of Chelone viridisj “ Challenger ” series, 
yoI. i., part 5, plate 6 , figs. 6 , 6a). 
