DEVELOPMENT OF THE SKULL IN THE BAT RAC HI A. 
137 
The prootics and ex-occipitals (e.o. to Y.) are one undivided mass of bone, right and 
left, and the tracts are margined by cartilage, outside and in. 
The outer tract, above, is the widish oblong tegmen tympani ( t.ty .), beyond the 
horizontal canal ( h.s.c .); below, the vestibular region ( vb.) is largely unossified. 
In front, the bone reaches to the foramen ovale (V.). Thence the cranial trough is 
unossified for three-fifths of the region of the orbits ; in the hinder half of this tract 
the optic fenestra ( o.s ., II.) is very large. 
The girdle-bone (eth.) does not ossify all the ethmoidal region in front; it reaches 
further below than above, and there it projects somewhat into the “ wings,” and 
reaches forwards most in the middle. 
The fore part of the great, single, open fontanelle (fo.) cuts away a semi-circle from 
the girdle-bone ; three-fourths of it is uncovered by the arrested roof-bones. The fore 
part of the ethmoid and all the nasal territory is unossified; the septum nasi (s.n.) is 
large and clearly marked, and the subnasal laminrn (fig. 2. s.n.l.) are very large, even 
at their narrowest part, mesiad of the internal nostrils (i.n.) ; their notched outer 
edges nearly reach these passages. The “intertrabecula” only forms as a knob in the 
prenasal region ; the angles of the subnasal laminae are triangular, and spread into 
the maxillaries at their fore end. 
The secondary cornua, or pro-rhinals ( p.rli .), are long, slender, and out-turned. 
The nasal i’oof-cartilages form a mere rim to the septum nasi (fig. 1, al.n., s.n.), but 
they swell out into a curious bag of cartilage in front. This bag lies on the fore part 
of the subnasal lamina, and is confluent with it; the premaxillary encloses part of 
this bag, as well as the pro-rhinal band. 
The thick upper and fore part of the nasal roof stops abruptly, the cartilage dipping 
down in front; after forming the bag, it grows up again, behind the large outer nostril 
(e.n.), which is protected, in front, by the three-toothed outer and upper labial ( u.l 2 .) ; 
this is attached to the inner labial ( u.l h), a large oval segment, inside the nasal process 
of the pre-maxillary. 
These nasal pouches look like those of Dactylethra, but in that type these bagpipe¬ 
shaped pouches are formed out of the large upper labial; the true nasal roof being 
a small band over the nasal sac, on each side (see Phil. Trans. 1876, Plate 59, figs. 1, 
3, 5, and 6, u.l.). 
The ethmo-palatines (e.pci.) are wide, diverging, cultrate bands, emarginate in front, 
with a wide pre-palatine blade ( pr.pa .), and having the post-palatine bar ( pt.pa.) 
continuous with the pterygoid as one arcuate cartilage, but little afiected behind by 
the normal pterygoid bone ( pg.). There is no palatine bone, but the pterygoid runs 
far forwards; behind, it bifurcates as usual, to invest the large pedate pedicle (pel.), 
and to clamp the inside of the quadrahe stem (fig. 2, sp.) This region is only a little 
affected by the quadrato-jugal (q.j.) ; its condyle ( q.c.) is small, but normal; it reaches 
only a little behind the very small Eustachian pouch ( eu.). 
There is neither annulus tympanicus, or columella ; the stapes (figs. 1 and 4, st.) is 
MDCCCLXXXI. T 
