DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 85 



In the rounded angle between these two forks we see the large, oval, oblique, 

 Eustachian opening (('».) ; this is enclosed behind, by the geniculate stylo-hyal {st.li,.). 



The suspensorium forms a very obtuse angle with the axis of the skull, and its 

 condyle reaches to a transverse line that cuts the neck of the occipital condyles. 



The hinge {q.c.) is a bilobate condyle, the inner lobe being the larger ; the substance 

 of the cartilage above the condyle is ossified as a quctdrate hone, by the engrafting on 

 it of the " quadrato-jugal " {qj-)- 



A tract of cartilage can be seen outside the pterygoid (fig. 3, pg.), and this may be 

 traced into the pedicle, and to the hoi- rowed quadrate centre. 



The backward position of the suspensorium is the cause of the very tilted position of 

 the squamosal (fig. 3, sq.), the lower part of which, partly hidden by the ear-drum, runs 

 backwards as well as downwards ; the supratemporal part (fig. 3, sq.) is very long and 

 sigmoid, for it sends forwards a sharp out-bent postorbital process. 



The premaxillaries (px.) are large and well formed, having a well-defined dentary 

 margin, a triangular palatine process, and a high nasal process, capped, inside, by the 

 inner upper labial. 



The dentary edge of the face is finished by the maxillary, the teeth ending 

 opposite the Eustachian tubes, and the bone opposite the middle of the auditory 

 capsules. 



There are small " septo-maxillaries {s.mx.)," and the maxillaries [mx.], notched in 

 front, run well up to the premaxillaries and the nasals ; the jugal part is high. 



The quadrato-jugals (q.j.) are short, high, and are grafted upon the quadrate region 

 of the suspensorium, as aforementioned. 



The cartilaginous mandible is placed obliquely in its "articular" trough (ar.), that 

 bone lying mainly below, and on the inside ; the dentary (d.) has formed a " mento- 

 Meckehan" bone (fig. 3, m.mJc.), by ossification of the end of tlie rod ; once the free 

 inferior labial ! 



The stapes (Plate 10, fig. 4, st.) is thick and reniform ; for the antero-superioB 

 edge is sinuous to admit of the large dorsal part of the " columella," between it and 

 the capsule. 



The inter-stapedial end of the columella is thin and clawed below ; the upper part is 

 large and blunt ; by these it holds the stapes, as it were. 



The " medio-stapedial " bone {m.st.) is dilated where it runs into these spurs, and 

 then runs as a straight rod up to the extra-stapedial {e.st). This latter part is at first 

 no thicker than the end of the bone from which it arises ; it turns downwards, and 

 soon enlarges into a tranversely oval disc. 



There is no " supra-stapedial," even as a membranous band, and the interstapedial 

 also not being segmented off, this columella is much below the normal condition. 



The "annulus tympauicus " (pJij.) is large, and its horns nearly meet above. 



The stylo-hyal end of the cerato-hynl band {st.h.) has coalesced with the auditory 

 capsule, a moderate space from the front of the fenestra ovalis ; it then turns directly 



