MACROPOMA. 175 
inferior angle to meet the end of the suborbital. Like the latter element, it is of 
very open texture, with only a sparse tubercular ornament; and it is not marked 
by any well-defined groove for a slime-canal, though its upper half is impressed by 
a Shallow fossa, which often appears in the fossils as if it were a vacuity in the 
bone, extending obliquely inwards and backwards from the antero-superior angle. 
The middle postorbital is not so deep as wide, and tapers a little forwards. The 
lower postorbital is much more elongated antero-posteriorly, truncated behind, 
pointed in front, and more closely tuberculated than either of the others. 
The mandibular suspensorium is nearly vertical, so that the gape of the mouth 
is wide. As usual in the Coelacanths, the hyomandibular, quadrate, and pterygoid 
bones are fused together on each side into a thin triangular plate, which articulates 
loosely in an elongated suture with the cranium. This articulation extends as far 
forwards as the front end of the parietal region, the anterior upper angle of the 
hyomandibular being considerably produced. The complete form of the plate can 
be determined from the specimens shown in Pl. XXXVII, figs. 1, 4. Its outer 
face (fig. 1, p/g.) is smooth, and the hyomandibular portion is strengthened by two 
vertical ridges which converge a little below. Its inner face (fig. 4) is densely 
covered with minute tubercular teeth, and the entopterygoid portion must have 
inclined inwards to form the roof of the mouth. The quadrate portion, which is 
completely shown from the inner face in fig. 4, is produced postero-inferiorly mto 
a constricted prominence, which ends in a large ginglymoid condyle for articulation 
with the mandible. The anterior end of the pterygoid portion tapers to a thin 
edge, where it meets another lamina of bone, which bears relatively large conical 
teeth on its lower border, and may probably be interpreted as the palatine element. 
The maxilla (Pl. XXXV, fig. 10, mx.) occurs outside the lower border of the 
pterygoid plate, just beneath the suborbital. It is a narrow bar of bone, ornamented 
externally with a fine, close granulation, and bearing an irregular series of incurved 
conical teeth on its margin; but its complete shape and extent are unknown, and 
no specimen hitherto discovered exhibits a premaxilla. Of the mandible, each 
ramus 1s long and slender, deepest in its middle third, and specially remarkable for 
the large size of its inner space which would be occupied by the meckelian cartilage. 
It appears arched on account of the shght concavity of its lower margim and the 
rounded contour of its outer upper edge (see especially Pl. XXXVIT, fig. 5). Its 
outer face is traversed below by a deep and wide longitudinal groove for the slime- 
canal. The angular bone (Pl. XXXV, fig. 9; Pl. XXXVII, figs. 5, 6, ag.) forms 
nearly two thirds of this face, rising to a considerable depth in its middle portion, 
but tapering to a point in front and to a somewhat more blunt ending behind. — Its 
upper margin is gently curved, and its outer pitted or reticulated face is more or 
less sparsely tuberculated. The anterior end of the angular passes in an oblique 
suture below the posterior tapering extremity of the dentary, which completes the 
mandible in front. The latter bone (Pl. XXXV, fig.9; Pl. XXXVII, figs. 5, 7, d.) 
coo) 
