DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
133 
the quadrate (q .)—the latter is partly ossified near the trochlea or condyle ( <[.c .) 
by the quadrato-jugal (qj)- 
The Eustachian openings (eu.) are large, reniform, and transverse ; the annulus ( a.ty.) 
is large and its horns are confluent, above. 
The stapes (fig. 5, st.) is large, truncate in front, and has a large knob for muscular 
attachment. 
The inter-stapedial (i.st.) is well developed as a “sesamoid” cartilage; the medio- 
stapedial ( m.st .) is roughly pistol-shaped; the extra-stapedial (e.st.) is a large spatula, 
giving off a ligulate supra-stapeclial ( s.st .), which is confluent, above. 
The mandible (fig. 3) is normal, but the dentary (d.) is much longer than usual, 
and the articular portion has an endosteal “ articulare ” (ar 1 .) as in Bombincitor. 
The basi hyo-branchial plate (fig. 4) has the notch very deep; the cerato-hyals 
( c.liy .) expand to twice their upper size, in the middle, and have a small hypo-hyal 
lobe ; they are free above. The lateral lobes, fore and hinder, are well developed, 
but the thyro-hyals ( t.hy .) are near together in front, and are short; they have a 
pedate unossified free end, and each has, on its outside, a small oblong nucleus of 
cartilage sticking to the bony shaft.* 
Here again we see, as in Pelodytes, the V-shaped perichrondrial bone, with its angle 
backwards, lying on the under face of the basal plate near the thyro-hyal; it is an 
attempt to form a basi-branchial bone. 
The investing bones correspond very closely with those seen in the skulls of 
Pelodytes and Bombincitor, and they are also very similar to those of the more 
delicate Australian Hylce. The fronto-parietals (fp.) are thin laths of bone, lying 
on the skull-wall, and curved so as to bind round the two fontanelles and the front 
of the ear-capsule, just at its inner edge. But they fail to cover the superoccipital 
region, and only partly hide the girdle-bone. 
The nasals (n.) have the usual form, and in their fullness of size and shape cover 
in the imperfect nasal roof. 
The premaxillaries (px.) are extended widely ; the maxillaries, quadrato-jugals, and 
squamosals (mx., q.j., sq.) are normal but feeble ; the quadrate is partly ossified by the 
second of these; the third only binds on the edge of the tegmen tympani. 
The parasphenoid (fig. 2, pa.s.) is large in its fore part, but its wings are narrow 
externally, and the hind part is but little produced. The vomers (v .) are very large, 
but in this wide-muzzled Frog they only reach the septum nasi inwardly, and outwardly 
do not touch the maxillaries. The dentigerous part is oval and transversely placed; 
the interspaces between these tracts is almost equal to the tracts themselves. There 
are no septo-maxillaries. 
It is impossible to compare this skull with that of Bombinator and Pelodytes without 
seeing that these three have many things in common, and that in so far as they agree 
* Mr. Howes Las shown me, in his exquisite dissections of the Sturgeon at the South Kensington 
Museum, that the visceral arches of that fish have many small nuclei of cartilage inside the periosteum. 
