CCELACANTHIDiE. 
395 
The cranium of Macropoma , which may be regarded as a 
typical Coelacanth, is well ossified and provided with robust mem¬ 
brane-bones. The roof of the skull is divisible “ into two moieties, 
an anterior or frontal, and a posterior or occipito-parietal, which 
■ meet at an obtuse angle, the occipito-parietal moiety being nearly 
• parallel with the base of the skull, while the frontal .slopes obliquely 
forwards and downwards to the snout; the occipito-parietal portion 
is slightly convex from before backwards, and more so from side to 
side; while the frontal portion, though convex from side to side, is 
slightly concave from before back waids.” The occipito-parietal 
region comprises a pair of large bones meeting in the middle line, 
evidently to be regarded as parietals, flanked postero-externally by 
a pair of triangular bones, which appear to represent the squamosal 
fused with the post-temporal. The frontals are long and narrow, 
separated by a suture at The median line, and flanked on each outer 
margin by a single series of small quadrate membrane-bones, which 
have been named parafrontals. The chondrocranium itself is exten¬ 
sively ossified, but there is no interorbital septum ; and the base is 
formed by a long slender parasphenoid bone, which exhibits a spatu- 
late expansion anteriorly. 
The hyomandibular and pterygo-quadrate arcade are fused into 
a continuous triangular, lamelliform bone on each side, articulating 
with the hinder portion of the cranium above, and provided postero- 
inferiorly with a ginglymoid condyle for the articulation of the 
mandible below. The bone terminates in an attenuated angle in 
front, and its superior portion is inclined inwards, so that the inner 
surface forms the roof of the mouth; this surface is finely granu¬ 
lated and its lower border exhibits well-developed teeth, while the 
outer surface is smooth. In front of the pterygo-quadrates, a pair 
of thin small palatine bones, with more or less formidable teeth, 
occurs ; and immediately in advance of these is a large azygous 
robust element, beaiing a cluster of strong teeth, probably to be 
regarded as the coalesced vomers. The actual termination of the 
snout is not definitely known in Macropoma; but in the Upper 
Jurassic genera it is stated by von Zittel 1 to consist of a blunt 
rostrum, showing no sutures, and much resembling that of some 
of the early Dipnoi. The eye is surrounded by a ring of small, 
delicate sclerotic plates, suggestive of those of certain Palaeozoic 
Amphibia. There are two large quadrate cheek-plates, one above the 
1 Handb. Pakeont. vol. iii. p. 173. This description suggests that the 
undetermined snout from the Sussex Chalk noticed and figured by the present 
writer in Proe. Geol. Assoc, vol. xi. (1889), p. 31, pi. i, fig. 6, may pertain to 
Macropoma. 
