DEVELOPMENT OF THE SKULL IN THE BATRAC'HIA. 
07 
little. The narrow part opens out elegantly into the ethmoidal wings; up to them 
the girdal-bone ( eth .) reaches, ancl no further. Above, this bone reaches half way to 
the extended prootic tract; below, two-fifths of the walls are soft, and this unossified 
tract has in its middle a very large optic fenestra (II.), and behind, it encloses most of 
the foramen ovale (V.). 
The nasal region is quite unlike that of atypical Frog; above (fig. 1), the nasal 
roofs are very narrow, and merely form a crescentic selvedge to the septum nasi (s.n.), 
and on to the fore margin of the ethmo-palatine band. 
The narrow roof curls round the front of the outer nostrils (e.n.), which are very 
near each other—-only one-third the distance apart that we have just seen in the Frog 
from Lagos (Plate 13, fig. 7, e.n.); behind the opening the nasal wall ( n.w .) is thick 
and crescentic. 
This narrowing of the nasal end of the skull is made more remarkable by the 
development of a verydisti.net and pointed prenasal cartilage ( p.n .).* 
But below (fig. 2, s.n.l.), the trabeculae have united to form a very wide elegantly 
winged tract, which passes between the laminae of the maxillaries (mx.), externally : 
behind, it is narrowed, for each margin is cut away by a semi-circular notch, through 
which the internal nostrils (i.n.) pass. The “ pro-rhinals ” ( p.rh.) are very long, 
slender, and bent back upon themselves. 
These processes (Plate 15, fig. 5 , p.rh.) are impacted between the two laminae of the 
premaxillary; they are equal to the prenasal in thickness. 
The nasal valves ( u.l 2 .) are outside the nostrils; they are, in form, quite normal, but 
very small. 
The whole of the palato-suspensorial arch is quite normal, and rather slender; the 
same is true of the bony plates (pa., pg.). 
The pedicles (pel.) are wide apart, for the auditory masses are relatively large, and 
widely outspread. The condyles of the quadrate (q.c.) are a little further back than in 
the last, are opposite the end of the stapes, and are large and reniform ; there is no 
grafting of the quadrato-jugal over them. 
The Eustachian openings (fig. 2, eu.) are very large and are turned obliquely 
backwards, outside; the annulus is very large, and like that of the Bull-frogs (Eastern 
and Western). The stapes (fig. 4, st.) is large and like that of the “norma;” the 
columella is very generalised; there is no inter-stapedial segment at the scooped top of 
the club-shaped medio-stapedial (m.st.) whose interstapedial end (i.st.) is not ossified. 
By a short stem, the bony tract is connected, in front, with a small extra-stapedial (e.st.), 
which has no secondary process ; here, the breadth of the “ annulus,” below, is more 
than twice as great as that of the circular extra-stapedial: this is the converse of what 
is seen in Rana Kuhli and Dactyletlira. 
The investing bones are about as strong as those of the skull of “ the type,” when 
* The right dotted line from p.n. in fig. 1 points to the nasal process of the right premaxillai’y; behind 
its apex the first upper labial is hidden. 
