178 
MR, W. K. PARKER ON THE STRUCTURE AND 
parietal, squamosal, part of premaxillary, maxillary, palatine, and vomer (Plate 25, 
fig. 1, 7i., /, p., i.p., sq., pp.x., mx.. pa., v.). 
Ninth Stage.—Dissections of the shall of young Moles, 3 or 4 days old; 
if and If inch long. 
Dissections of the skull of the larger of these young (if inch long) serve to interpret 
the adult skull as well as any of the stages. 
The form of the skull is wedge-shaped (Plate 26), the widest part being very near 
the end, and the whole skull structure narrowing forwards to the growing snout. 
Seen from above (Plate 26, fig. 1), the normal investing bones are shown to increase 
in size from before backwards, very remarkably. The oblong nasals (n.) are of con¬ 
siderable width, but they are not so long as the uncovered snout in front of them; 
they are flanked by the premaxillaries and maxillaries {mx., px.). The small convex 
frontals (f.) added to these six bones of the face do not cover so large a surface as the 
two parietals (p.) ; which, together, form half a large ellipse. 
A considerable fontanelle (fo.) still exists along and across the skull in the frontal, 
coronal, sagittal, and lambdoidal regions; the last of these is the largest space, but it 
is partly filled up, behind, by a small semi-annulus of bone—the interparietal (ip.). 
Looked at from the side (Plate 26, fig. 3), other splint-bones come into view. In this 
view the premaxillary (px.) is seen to have considerable facial tract, interdigitating with 
the maxillary (mx.) and reaching up to the nasal (n.). The maxillary is notched by the 
frontal (f) and has the small heart-shaped lachrymal (l.) set into its orbital edge, where, 
also, the canal (Lc.) is seen just on the outer margin of the orbit. The canal for the 
2nd branch of the trigeminal nerve (V 3 .) is not finished, and behind and below the 
groove, first the jugal (j.) is seen as a small style, followed by the styloid jugal process 
of the small, oblique, multilobate squamosal (sq.). That bone is very peculiar in this 
small wedge-shaped skull, which is bent downwards, behind, at a considerable angle; 
nearly all the hinder half of the skull is unprotected by superficial bones, and the 
squamosal, thereby, forms a small adherent scale on its antero-inferior surface. 
Scarcely reaching the lower edge of the parietal in front, it recedes, downwards, from 
that bone, leaving a large triangle of the endocranium bare ; it is marked off into 
two regions, one in front and above, narrow and forked, and the other behind and 
below, wide and semi-ovate. 
The broad upper tract in front of the proper squamous part has a sharp point, the 
jugal process, which overlies the jugal bone (j.) ; under this fore part we see the 
glenoid cavity ( gl.c.). The lower and hinder lobe reaches by its rounded end nearly 
to the stylomastoid foramen (VII.) and quite to the ampulla of the anterior and 
horizontal canals of the ear (a.s.c ., h.s.c.). The lower edge, rising forwards, forms the 
eave of the tegmen tympani; under it is seen another superficial bone, the annulus 
tympanicus ( a.ty .), better seen from below (fig. 2). The frontal (f), half the size of 
