DEVELOPMENT OF THE SKULL IN THE MAMMALIA. 267 
(m.tb.) is seen thrusting itself forward over the feeble inferior, and under the small 
nasal, turbinals (7.tb., 7.tb.); here the cartilaginous part of the partition has been 
removed, and the front of the bony part (s.7.) is towards the eye; it is hollow below 
where it has not ossified, and rests upon the grooved vomer (v.) in front of the palatine 
processes of the premaxillaries (pz.). A vertical slice of the skull in the region of 
the meatus (Plate 39, fig. 6, a.ty., m.a.e.), and through the glenoid cavity (gl.c.), shows 
the large air-cells of the squamosal (sq.) and their somewhat radiating arrangement. 
In a part of the hind skull cut across horizontally (fig. 8) the air-cells of the 
squamosal and mastoid (sq.,op.) are shown ; where these two bony parts have coalesced 
behind, there the cells are very regular and their septa for some extent radially 
arranged. In this figure the parasphenoid (pc.s.), pterygoid (pg.), external pterygoid 
process (¢.pg.), and glenoid cavity (g/.c.) are shown. The tympanic lip, under the 
Eustachian tube (ev.), is not injured, but the dish itself is largely cut away and the small 
tympanic cavity (c.ty.) exposed, inside and above which is the small melon-like cochlea 
(chl.) and the fenestree (fs.0., fr.), and also the opening for the 9th, 10th, and 12th 
nerves (IX., X., XII.) ; the latter are very large, but are only seen obliquely in front 
of the occipital condyle (0c.c.). 
The lower jaw of this beast might belong to some generalized Herbivorous 
Ungulate ; it is indeed almost a miniature of that of the Hippopotamus. ‘To say 
nothing of its unique pectinated front teeth, the general shape is very remarkable, 
with its depressed mentum, oblong ramus, short uncinate coronoid process, transverse, 
sessile condyloid, and deep out-turned angular, process, the edge of which is thickened 
inwards ; its whole shape is half a circle. 
The malleus (Plate 39, fig. 7, m/.) has lost all its processus gracilis (p.gr.), except 
one or two sharp prickles ; the manubrium (mb.) is strong, curved, dilated at its end, 
and sinuous outside. The incus (7.), like that of the Ruminants, has a heavy, solid 
body, with short processes (s.c.7., /.¢.7.,); the stapes (st.) is somewhat inflated and 
hollow behind, and at its base oval ; there is a minute interhyal bone in the tendon of 
the stapedius muscle (7.hy., st.in.). 
The hyoid bone (Plate 38, figs. 9 and 10) shows a hypohyal as large as the cerato- 
hyal (h.hy., e.hy.). The basal bar (b./.b7.) is concave in front, and has a right and left 
tubercle hehind ; the thyrohyals (¢.hy.) are large, uncinate, and separate, as bony tracts, 
from the base ; all these bones are flat and splintery. 
On the skull of the adult Tupaia Javanica. 
This is another very isolated form of the Insectivora; I can only mention here 
certain peculiarities of the structure to be seen in the adult skull, hoping at some 
future time to be able to describe its development. 
The Tupaia is another instance to be added to Rhynchocyon and Galeopithecus, in 
which a clear prophecy of higher signs of development is combined with characters 
2m 2 
