DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
223 
As in the immature skull lately described (pp. 210-212), the length and breadth 
are equal, but the quadrate condyles ( q.c .) reach further back, viz.: up to the fore end 
of the stapes (st.)] a position soon attained in the young Toad. 
The occipital condyles ( oc.c.) are large, moderately wide apart, and postero-inferior, 
and the foramen magnum is large, as in the last (fig. 7). The auditory capsules are 
also, relatively, large, and have a small, oblique tegmen ( t.ty .), the whole parotic region 
being limited to an ear-shaped process of cartilage projecting beyond the horizontal 
canal ( h.s.c .), and nearly covered by the squamosal ( sq.). The canals project consider¬ 
ably ; in the epiotic and prootic regions ( p.s.c ., a.s.c.) equally. 
Below (fig. 2), scarcely any cartilage is left in the ear-capsules, except at the sides 
(fig. 3); hut there is a distinct tract for the facet on which the pedicle (fig. 2, pd .) 
glides. Above (fig. 1), the oblique, bevelled, outer margin is soft, and, in its defi¬ 
ciency, shows the stapes (st.) and mouth of the vestibule (au.) from that aspect. A 
wide and rapidly widening space of cartilage remains both in the basi- and supra- 
occipital regions (figs. 1, 2), but the bony tracts are thoroughly continuous, right and 
left; this is a generalised character. 
The prootic region of the bone (pr.o.) reaches half way between the 5th and optic 
nerves (V., II.), and, above (fig. 1), the bony matter only leaves a cartilaginous selvage 
round the large, elliptical, single fontanelle (fo.), which reaches, behind, to the middle 
of the anterior canal (a.s.c.), and in front ends nearly opposite the ethmoidal wings. 
The mid skull is widish, almost oblong, widening before and behind, and slightly 
bulging in the middle ; it is of moderate depth (fig. 3) and very long; for the skull is 
long, and the bulk of the nasal region short. 
The girdle-bone (eth.) is less than the cartilaginous part behind it (o.s.), in which is 
seen a very large optic fenestra (II.); as in many of the arrested types, the wall of the 
mid skull opens, as it were, to the setting of the eye-balls, as the hind skull does for 
the ear-balls. 
The ethmoidal wings are only partly ossified, right and left; below (fig. 2), the 
ethmoidal region is ossified to its end; above (fig. 1), the bony growth creeps along a 
third of the true nasal region. 
The tegmen cranii is very limited before, behind, and at the sides, so that the 
fontanelle is very large and long. 
The nasal roof (n.r.) is relatively very wide, as in most young Anura; the floor is 
about three-fourths as wide (figs. 2 and 4, n.f.). The roof overhangs the fore face, as 
in many of the edentulous types, and here there is a very generalised and very Ravine 
prenasal rostrum (p.n.), which has, evidently, shrunk from the cavity of a (once) long 
dermal beak, noiv an oval leaf of skin projecting from the nose.'"' 
The pro-rhinals (p.rh.) are small; the valves (u.V-.uR.) large; the whole region, 
stripped of the investing bones (fig. 4), is seen to be very much like that of the Skate ; 
* I believe that this type has become dwarfed, and its rostrum shrunken as a correlative of the new 
bony tracts that have appeared in and on the chondrocranium. 
