OF THE SKULL IN' LEPIDOSTEUS OSSEUS. 
471 
the deep, palatal chink; this is the fore part of the frontal. Below this there is 
one of the maxillary chain (mx'.) cut through, protecting a gland; and inside this, 
on the lateral lobe of the beak, there is a wedge-shaped tract of fine diploe, the lower 
part of which carries a large tooth ; this tract is the palatine {pa'.) cut through. In 
the triangular median keel of the beak there are three thin plates cut through ; two of 
them are superficial and the third is deeper, taking the form of the rostrum somewhat, 
hut diverging externally, and having a short crus below—this is the parasphenoid 
( pa.s .). The paired laminae running downwards and inwards, outside it, are the 
vomers (v.) in their widest part; they are overlapped by the inner end of the frontals, 
externally; which, at their outer end, overlap, obliquely, the sharp end of both the 
cornua trabecula? and the pterygoid cartilages {p.pg.). Below, the thick lower jaws 
have in them the section of the Meckel’s cartilage {mk.), large and almost circular. 
There is here the flat, double tongue, with its soft basi-hyal (b.hy.), also double. On 
each side of the tongue there is a deep sulcus. The splenial bone (spl.), over and within 
the cartilage, is here at its largest size, and the dentary (d.) takes up a large space by 
its reticulations ; it encloses a mucous gland below. 
Section 6.—This section (Plate 35, fig. 3) is through the angle of the mouth, and thus 
the upper and lower tracts are continuous; the lower or mandibular region is of great 
height, being cut through close in front of its huge coronoid region. Here the cornua 
trabeculae {c.tr.) are at their thickest part, or middle (Plate 34, figs. 1, 2, c.tr .) and are 
continuous by a thin oblique tract, with the rostrum (i.tr.) which is at the thickest 
part in this and the next section. Here it is semi-elliptical above, and sub-carinate 
below, and the thin edges of the cornua ascend to their thick outer part; the olfactory 
nerves (I.) lie in the hollow between the bars. A little below the cornua the ptervgo- 
palatines ( P-pg •) are cut through; they are oval in section, their oblique position is 
parallel with that of the cornua, and their size is nearly as great. The mandibles 
{mk.) are oval in section, here, and twice as thick as the pterygo-palatines ; the basi- 
hyal {b.hy.) is here at its widest part. The laminae of the ethmo-nasals {et.n.), and of 
the frontals {/.) run close to each other, and below the pterygo-palatine there are two 
tracts of reticulated bone ; these are the palatines (see fig. 2, pa'.) below, and the ptery¬ 
goid ( pg.) above. The splenial {spl .) is here at its widest part, and the dentary {d.) is 
composed of a large strip of bone, externally, and of a wide network, below. 
Section 7 .—The position of this section (Plate 35, fig. 4) is evident, for it is through 
the thickest part of the coronoid process of the mandible (Plate 34, fig. 4 cr.c.) where 
this remarkable crest is separated from the main rod by a large rounded notch. Here 
the cornua trabeculae {c.tr.) are thinning out, behind, and the intertrabecula {i.tr.) is most 
solid, it is quite round above, and sub-angulate below. The pterygo-palatines {p.pg.) 
are oval and are further from the narrowed cornua {c.tr .)—they are twice as near to 
the coronoid cartilage {cr.c.) Below that crest,—which is placed obliquely across the 
face a little tilted upwards, and the section of which is oblong, but hooked inside— 
the main bar {mk.) is a large nearly vertical ellipse ; here the basi-hyal {b.hy.) is very 
MDCCCLXXXII. 3 P 
