174 FOSSIL FISHES OF THE ENGLISH CHALK. 
and Text-fig. 49), as usual im Coelacanths, form a continuous shield, the parietal 
region bemg in a plane nearly parallel with the basicranial axis, the longer and 
narrower fronto-ethmoidal region descending from this at a sharp angulation and 
ending in a somewhat spatulate snout. The parietal region (pa.) 1s twice as wide 
behind as in front, and its maximum width somewhat exceeds its length. Its 
hinder margin is excavated by a re-entering angle, into the middle of which a small 
point projects backwards ; its short anterior margin unites in a straight, transverse 
suture with the frontal region. Transversely it is strongly convex, with a mesial 
flattening, and its outer surface is more or less spongy in texture, with a longi- 
tudinally-fibrous tendency near the hinder margin, the whole ornamented with 
sparse, small tubercles of ganome. It is divided by a straight, median, longitudinal 
suture, which always persists ; and its postero-lateral prominences are also probably 
separated by suture, though this is not clear. The frontals (/7.), similarly divided 
by a straight, median, longitudinal suture, are relatively small, and their tumid 
surface is nearly smooth, though sparsely covered with tubercles of ganoine. 
Together they are longer than wide, and they unite in front in a conspicuously 
dentated suture with the large, irregular plates on the ethmoidal region (eth.). 
Of these plates there are about three successive pairs in advance of the frontals, 
and round them are arranged smaller irregular plates, which also extend backwards 
in a single series along each outer edge of the frontals as far as the parietals. 
Nearly all the plates are more or less coarsely pitted, though they bear the usual 
sparse ornament of tubercles. The parasphenoid, which forms a nearly straight 
basicranial axis, is a very narrow bar in the interorbital region (Pl. XXXVII, 
fig. 1, pas.), but expands forwards into a long spatulate area, densely covered with 
minute tubercular teeth, which are slightly enlarged along the margin of the bone 
(Pl. XXXVII, fig. 2). Immediately in advance of the parasphenoid, just below 
and in front of the prefrontal ossification, there is another expanded bone bearing 
a cluster of larger blunt teeth, which are hollow and smooth and often exhibit 
wear at the apex. This bone (Pl. XXXVII, figs. 3, 38 @) is comparatively thick, 
especially at its outer angles, and appears to consist of a pair of elements fused 
together, probably the coalesced vomers. Its oral face (fig. 3 a) 1s nearly triangular 
in shape, twice as wide as long, with the apex forwards. The cheek is covered with 
bony plates, of which the narrow, arched suborbital is always the most conspicuous. 
This plate (Pl. XXXV, figs. 9, 10, so.; Pl. XXXVI, fig. 1, so.), which is nearly 
uniform in width, except at its anterior expansion, is of loose texture, coarsely 
pitted on its outer face and excavated in front with two deep cavities, which 
indicate a considerable development of the slime-apparatus. It is ornamented with 
a few sparse tubercles. There are three postorbitals, which are always imperfect 
in the fossils, but seem to have been arranged as shown in Text-fig. 49. The 
upper plate (Pl. XXXV, figs. 9, 10, po’.; Pl. XXXVI, fig. 1, po’.) is the largest, 
at least as deep as wide, and nearly square, but slightly produced at its antero- 
