DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
231 
on each side; these are the lateral rudiments of the girdle-bone (eth.). These cochleate 
tracts reach the top of the cranial wall for a small extent, and also run into the 
ethmoidal alse, but they are far apart, above and below. These are the true “ lateral 
ethmoids,” but between them the “ perpendicular plate ” is in rudiment; this is a 
triangular tract of imperfect bone at the middle of the floor, just over the front 
of the parasphenoid (fig. 2, pa.s.). The fore part of the chondrocranium is well 
developed, but quite unossified; the subnasal laminae ( s.n.l.) are broad, with large 
falcate angles, and well formed pro-rhinals (p.rh.); the roof (n.r.) is well developed, and 
has a distinct ring of cartilage round the outer nostril ( e.n., n.w.) ; these passages are 
at a moderate distance, and are well protected by the labials ( udd.u.l 3 .). The palato- 
suspensorials are largely developed in front, for the ethmo-palatine bar (fig. 2) expands 
into a large adze-shaped plate, the pre-palatine part of which (fig. 4, e.pa., pr.pa.) 
almost reaches the angle of the nasal floor. There is just a thread of bone answering 
to the palatine ectostosis (figs. 2 and 4, pa.). 
The partially retreated hinder part of this arch is still continuous with the basis 
cranii by the unabsorbecl pedicle (pel.); the joint-cavity is there, but is not complete— 
as in the species of Bufo and other types, where the strong pterygoid binds this part 
down. Here, however, that is not the cause of the unfinish of the joint, for this bone 
(pg.) is very feeble as in young Toads and Frogs. 
The condyle of the quadrate (q.c.) is a large bilobate trochlea; the body of the 
suspensorium (fig. 6, sp.) is not ossified. There is a small ligulate sub-crescentic 
“annulus tympanicus” (figs. 5 and 6, a.ty.), but no columella. 
The stapes (figs. 5, 6, st.) is large, oval, and apiculate, behind;, the stylo-hyal ( st.h.) 
is loosely attached to the capsule. 
The rest of the band is wider (fig. 3, c.hy.) and is definitely dilated before it turns 
back as the hypo-hyal (h.hy.). 
The notch in front of the basal plate ( b.h.br.) is shallow, the plate itself short, the 
fore side lobes large and stalked, the hind side lobes very short, and the thyro-hyals 
(t.hy.) large and moderately divergent. 
The mandibles (fig. 3) are quite normal, but the ossified labials (m.mk.) are very 
large, and so are the articular condyles (ar.c.) ; the articular bone (ar.) rises directly in 
front of the condyles, but very little in the coronoid region; the dentary (d.) is small 
and feeble, and the rod of cartilage (ink.) is not much affected by the bone, outside. 
The investing bones are all in a quasi-juvenile condition; the fronto-parietals (f.p.) 
remain distinct, right and left; they more than cover the large fontanelle, and overlap 
the auditory capsules and super-occipitals moderately. 
The nasals (n.) are thin shells of bone, imperfectly covering their own region ; the 
premaxillaries, maxillaries, quadrato-jugals, and squamosals (px., rnx., q.j., sq.) have 
all the same feeble arrested character. 
So, also, the parasphenoid ( pa.s.) ; it has all its processes but is only two-fifths the 
length of the skull, and is less developed than that of the Tadpoles of many kinds. 
