DEVELOPMENT OF THE SKULL IN THE BATRACHTA. 
] 09 
The pterygoid (pg-), on the other hand, has used up most of the cartilage to which 
it clings, and growing beyond the pith of the pedicle (pel.) makes this part pointed. 
On the right side, that independent ossification of the outer and inner elements 
which is so common in the “ Anura,” shows itself in a remarkable manner, for the very 
apex of the cartilage becomes detached, as a “meniscus,” and then thoroughly ossified, as 
a small, free, diamond-shaped “metapterygoid” (figs. 5 and 5a , pd., pd.m.). In Rana 
temporaria, and others of that genus, the metapterygoid, which appears during 
metamorphosis, is formed in the outer fibrous layer : here it is endoskeletal. The 
quadrate region is neither long, nor far retreated (fig. 2, q.c.), it is all ossified by 
the quadrato-jugal, except the apex of the otic process, which is continuous with 
the slight remaining pith of the pterygoid, and the edge of the tegmen tympani 
(fig. 5, sp., q., pg.c., pr.o.). The condyle (q.c.) which ends opposite the middle of the 
stapes ( st .) is a large, well-formed trochlea, strongly clamped on its inner side by the 
pterygoid. That process forms a very obtuse angle with the pedicle, and here a very 
small crescentic slit can be seen just through the skin of the mouth, its convex side 
lying against the bone : this is the blind Eustachian opening ( eu .). Outside the 
suspensorium a very small annulus (figs. 3 and 6, a.ty., m.ty.) is seen ; it forms three- 
fourths of a circle, its diameter, and the breadth of the hand, is about one-third 
that of a typical Frog. 
The mandible (fig. 3) is very strong, especially in its hinder part; it is, however, 
quite normal. 
The stapes (fig. 6, 5i.) is of the average size ; it is a very regular oval, but has a 
rounded process behind, and an oval “ boss ” outside. 
The columella is extremely delicate, and is not segmented. The medio-stapedial 
bone ( m.st .) occupies the dilated stapedial end, and runs along the thread of cartilage 
so as to be one-third the length of the whole rod, which ends as an arcuate extra- 
stapedial (e.st.) ; this is spatulate, and without a fork. 
The stylo-hyal (fig. 2, s.th .) is confluent with a trace of cartilage on the outside of 
the floor of the vestibule; it enlarges in its descent (fig. 4, c.hy.), and becomes partly 
ossified. There is a small, sharp hypo-hyal lobe (h.hy.) in front, and one on the side of 
the short retral part; between these bars the “ notch is a very large crescent. 
For the basal plate is very wide and short, and is of the same kind as we see in 
Ccdyptocephalus (Plate 21, fig. 4)—a near relative. There is an adze-shaped fore, and a 
styliform hind, lobe on each side; the thyro-hyals ( t.liy .) are large, dilated, and separated 
by a space which is two-thirds of a regular oval. The proximal part of these bars take 
up half the basal plate, and they almost meet at the mid-line. The rest, all but the 
front edge and part of the fore-lobes, is semi-osseous. 
Like some other sub-typical Frogs— Pleurodemci, Lymnodynastes —the fronto- 
parietals ( f.p .) do not finish the roof but are scanted in their front half, and end as 
rounded bars, each one-third the breadth of the roof. Behind, they are strong, 
smooth, sinuous, falling in at the temples, and swelling over the anterior canals, and 
