DEVELOPMENT OF THE SKULL m THE TJEODELES. 193 



suspensorium is bifurcate ; and both the forks are confluent with the endocranium (the 

 trabecula and its alisphenoidal crest). The part confluent with the base is the pedicle 

 (jxZ); that which passes into the wall is the ascending process {a. 2)); outside these, 

 above, we have the otic process (ot.j)), which is confluent with the auditory capsule and 

 the preauditory horn. The body of the suspensorium (s])) is a suboval mass, set on the 

 thick bifurcate stalk ; the condyle (q.c) is subpentagonal, subconcave, and has its outer 

 margin lower than the inner. 



The suspensorium, having no pterygoid outgrowth, and no correlated pterygoid bone, is 

 naked below ; above it is covered up to the selvedge by the dilated squamosal (sq). The 

 condyle of the articulare (PI. XXXIX. fig. 1, at: c) is very high and convex externally, 

 slopes inwards, has a subconvex lower surface, and is subpentagonal in outline. 



The rest of the arch (PI. XXXIX. fig. 3, mk) is an undiminished Meckelian rod, 

 lying in a trough formed by the dentary {d) outside, and the articulare {ar) on the 

 inside ; the latter has a large angular process, and is but little grafted on the cartilage. 

 The rods nearly meet at the chin, where the dentaries are very solid ; the articulare 

 goes nearly as far as the cartilage. The splenial {spl) splices the rod for two thirds of 

 its fore part, which is bent at an obtuse angle on the hinder part ; this is the only 

 dentigerous bone in the mandible, and is a very small oblong piece. The mandible 

 is bent dovm at an obtuse angle from the point, where it rises into a considerable 

 " coronoid process." 



The notched, flat end of the stapes {st), whose general direction is outwards and 

 backwards, is curved so as to pass into the hinder part of the broad suspensorio- 

 stapedial ligament {s.s. I) ; this band widens forwards, and is attached to a lanceolate 

 cartilage, half of whose anterior margin, above, is confluent with the suspensorium. 



This cartilage is the epihyal {e.hy.), and may answer to the extrastapedial and medio- 

 stapedial in one piece, or possibly only to the former, the distal part of the stapes possibly 

 having the " pharyngohyal " element fused with it, which part would correspond to the 

 mediostapedial. 



Another broad ligamentous band (" hyosuspensorial " /«.s. Z) arises on the epihyal 

 cartilage {e.hy), and is inserted down the side of the front of the unossified upper 

 part of the ceratohyal {e.hy) ; the seventh nerve (vii) passes over this cartilage and 

 this band. 



The hyoid bar is also connected with the angle of the lower jaw by the " mandibulo- 

 hyoid ligament {m.h. I). This is a shorter band ; and it passes inside the last, and is 

 inserted in a fan-shaped manner on the outside of the middle of the cartilaginous 

 tract. 



This lower part (PI. XXXIX. fig. 3, e.hy) of the hyoid arch is longer than, and nearly 

 as thick as, the mandible ; its lower half is ossified as a round phalangoid shaft, nearly 

 to the end, whilst the upper half is a flatter and somewhat sigmoid tract ; there is no 

 separate hypohyal. 



The basal bar is divided into two parts, of which the foremost is one third larger 



