DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 141 



and angles of subnasal laminaj {p.rh., s.n.l.) — are not ossified. The pro-rhinals are 

 triangular, pointed and in-turned, as in the genus Bufo; inside them the passages 

 {n.n.) for the terminal branches of the " orbito-nasal" nerves are large. 



The thick roof hides the fontanelle, but I suspect it to be single, as in the thin skull 

 o{ Bombinator (fig. 1). 



That I should claim for the pterygoid and palatine bones {;P<J-,p(i-) the title oi' endo- 

 skeletal and " ectosteal " will not seem very strange if the condition of these bones in 

 Pelohates is considered. All, or nearly all, the cartilaginous palato-suspensorial arch 

 has been eaten by these strong bones. Here the palatine (fig. G, pa.) has the form of 

 a hatchet blade, for it has taken up the prenasal spike ; it is deeply notched, and 

 half the long-oval, transverse inner nostril l^i.n.) is in this notch, and the hole is finished 

 inside by the vomer and wing of the ethmoid (v., eth.). Curving elegantly round in the 

 hollow of the maxillary (jnx.) the palatine meets the pterygoid {pg.) ; seen from below, 

 these two bones appear of equal length : a thing contrary to rule. 



The pterygoid (fig. 6) has the strength of a " flying buttress," jammed in between 

 the dentary and palatine laminae of the maxillary (inx.), and then springing obliquely 

 across to clamp the front of the hind skull over the reduced and useless " pedicle," it 

 fixes and binds the cheek to the cranium. That inner fork, like a strong foot, stands 

 stoutly on the prootic, and is sutured to the parasphenoid (fig. Q, pr.o., pa.s.). The 

 outer fork passes back outside the minute Eustachian pouch (eu.), and clamps the 

 inside of the quadrate {<].), the distal part of this huge "pier." By grafting of the 

 quadrato-j ugal (qj.) on the cartilage, this part also is well ossified, all but the large 

 convexo-concave reniform condyle {q.c). 



Answering to its piei-, the mandibular arch (fig. 10) is unusually stout; yet it does 

 keep the Meckelian rod — its pith — unossified. The mento-Meckelian {m.mk.) is well 

 developed ; the dentary {d.) is continued from it as a strong splint along tlie front 

 two-thirds of the arch ; and the " articulare " (ar.) forms a strong inwardly crested 

 trough for the primaiy cartilaginous rod. • 



I can find no " annulus tympanicus;" the spiracular cartilage is probalily combined 

 with the edge of the " tegmen." The stapes (figs. 8 and 11, at.) is rather large and 

 has an " umbo ;" its form is three-fourths of a circle, with the hind margin cut away 

 to fit against the sub-convex bony margin of the fenestra ovalis, behind. The columella 

 {co. ) is a little phalangiform bone, as long as half across the stapes, thick behind, thin 

 in the middle, and knobbed at its free end ; it fits against the inferior margm of the 

 stapes, just below the facial nerve (VII.). The stylo-hyal (st.h.) has a pedate end which 

 articulates with the auditory mass close behind the minute Eustachian pouch (<?«.). 

 The continuation of the hyoid bar gently increases in size until it comes to the hypo- 

 hyal region (fig. 9, c.Jii/., h.hy.); that part is a large rounded ear of cartilage, which, 

 behind, passes by a broad stem into the basal plate {b.h.br.). The cerato-hyal has two 

 small osseous centres m it ; a rare modification. 



As in the Hylida^, the pre-basal notch is of great depth, and the basal phite of small 



