ENCHODONXID35. 
197 
Maastricht. The cranium is somewhat obscured and 
fractured, but the general characters of the cranial roof 
(PI. XI. fig. 6) can be observed. The plane of the occiput 
is about at right-angles to that of the roof, and the 
occipital border exhibits the five prominences characteristic 
of the higher fishes. The small median eminence, partly 
broken away, is formed by the supraoccipital bone (s.oec.), 
which seems to enter the crauial roof as a short and broad 
plate. The inner pair of prominences are formed by the 
large and robust epiotics ( ep.o .) ; the outer, or pterotie, 
prominences ( pt.o .) are broken, but the right side of the 
fossil exhibits a delicate plate of bone extending forwards 
and inwards presumably upon the pterotie element to the 
ridge on the frontal at the level of the hinder border 
of the orbit. The outlines of the parietal bones are 
not shown, and the precise limits of the hinder end of 
the frontals are uncertain. The frontals (fr.), however, 
extend remarkably far backwards, and are evidently 
ridged in the manner characteristic of the genus, though 
the inwardly directed triangular ridged area spreading 
backwards along the postorbital region is broken away. 
The ridges are all sharp, but not tuberculated, and the 
smooth median area occupies nearly the inner half of the 
bone. The elements of tho palato-pterygoid arcade are 
almost completely covered by matrix and the investing 
bones, though some of the teeth are partly seen. Tho 
delicate laminar premaxilla (fig. fia, pmx.) is imperfectly 
shown on both sides, and that of the right is fractured by 
being crushed on one of tho ectopterygoid teeth (a?.) ; 
it is a deepened plate of bone in its anterior half, tapering 
to a very slender production behind, and must have 
formed the margin of at least half the gape. It bears a 
regular close scries of very small teeth on its oral border, 
these being indicated by their bases on the left, by a few 
crowns on the right side. The very slender maxilla (mx.), 
best shown by a fragment on the right side, bears still 
smaller eloselv-set teeth. In its crushed state the region 
of the cheek on the left side is covered in front by two 
bones which cannot be satisfactorily determined. The 
foremost exhibits an external ornament of radiating lines 
of very fine tubercles, and may possibly belong to the 
opercular apparatus. The other is deep and narrow, with 
a triangular expansion below, exposed from tho inner 
