188 PROF. W. K. PARKER ON THE STRUCTURE AND 
bones for half their length; and two fifths of the frontals are between the fore half of 
the parietals. 
They are overlapped by two pairs of bones in front (pa, et.n); yet their fore part, 
nairowing in, reaches nearly to the point of the nasal sacs. 
These two pairs of bones, the frontals and parietals, form a shallow, sloping, but a 
scarcely crested roof; the latter rise most in the fore part of the sagittal suture 
(Pl. XX XIX. fig. 1, p). 
The median suture is continuous from the occipital ring to the premaxillary edge ; 
two submesial bones finish this suture in front; they are two thirds the size of the 
frontals, are oblong, have rounded ends in front, and are styliform behind, where 
they are intercalated with the frontals, and repeat the imbrication of those bones 
on and between the parietals. 
The right bone is the larger of the two. In the middle of their suture there is a 
small round passage, like the “parietal fontanelle” of a Lizard; this is the “middle 
nasal passage” (m. 7. p). These bones lie inside the nasal processes of the premaxillaries 
(px), and far from the rudimentary nasal roof (na); they are not the nasals, which I 
do not find in this species, but correspond to the two long, narrow, superethmoidal 
splints of the Pike (Huxley, Elem. Comp. Anat. p. 168, fig. 69, 3). Similar bones acquire 
an immense length in Lepidosteus. ‘They are represented by a single piece in a large 
number of types above and below the Urodeles (e. g. Clarias, Salmo, Iguana, &c.), and 
are simply “ dermo-ethmoids.” 
Embracing these bones, we see another pair of bones more than half as large, 
hooking round and close to their foremost two thirds, and appearing as small elliptical 
plates, which are covered with horn, and have no teeth, on the lower surface 
(Pl. XX XVIII. figs. 5, 6, px); these are the premaxillaries—symmetrical, but feebly 
developed bones. These bones meet in front, bending round the superethmoidal 
plates; and this front part, with its fellow, forms an arcuate tract below. The max- 
illaries (ma) are small seed-like centres opposite the middle of the premaxillaries. 
Another lateral bone is seen behind; this is the squamosal (sq), a falciform bone 
with its point behind and above clamping the epiotic “horn,” and discoid below, where 
it has taken on the form of the suspensorium, the articular region of which is dilated like 
a snail’s foot. This is a very simple subcutaneous scale, very much like a preopercular, 
but bent in the opposite direction, and modified by the curious distal dilatation ; it has 
no posterior process like that seen in the Menopome (Pl. XXXVIII. fig. 1, sg, and 
Pl. XXXTX. figs. 5, 6, sq). 
Beneath, the endocranium is almost completely floored by the parasphenoid ( pa.s) ; 
here this bone attains almost its greatest relative size, but it confines itself to the basis 
cranii; it is longer, relatively, in the Sturgeon, where it runs under the fore part of 
the spine. 
In the lower view (Pl. XX XVIII. fig. 6, pa.s) this bone is seen to be a large slab, 
