92 WEALDEN AND PURBECK FOSSIL FISHES. 



the hinder border of the orbit. As shown by the type specimen, the maxilla is 

 smooth and shaped as in Amia ; so far as can be seen in several specimens, the 

 mandible is also Amioid, the dentary bearing a single regular close series of smooth 

 high conical teeth. The preopercnlum, as shown in the type specimen, is a narrow 

 arched bone, nearly smooth; the operculum (B. M. no. 41171) must have been 

 nearly as broad as deep ; the suboperculum is somewhat more than half as deep as 

 the operculum, with a stout anterior ascending process ; the triangular inter- 

 operculum is broader than deep ; and several of the upper branchiostegal rays are 

 wide laminae. None of the opercular bones are marked by more than feeble coarse 

 rugae, which are seen to be radiating on the operculum of the type specimen. 



The vertebral centra are well ossified, and all are marked by two principal 

 lateral pits, one above, one below a longitudinal median ridge, which is impressed 

 with a variable number of comparatively small pits. In the abdominal region the 

 centra are about as long as deep, apparently without any processes for the support 

 of the ribs, which are short, stout, and curved. The neural arches in advance of 

 the dorsal fin are surmounted by the usual separate neural spines. In the caudal 

 region the vertebral centra are shorter and deeper, and some clearly alternate with 

 and without neural and haemal arches in the typical Amioid manner. The neural 

 and haemal arches are short, slender, and almost symmetrical until the base of the 

 caudal fin, in which about 14 haemals predominate both in length and in stoutness. 



The rays of all the fins are stout and smooth, and all are both closely articu- 

 lated and divided for the greater part of their length distally (PI. XIX, fig. 5). A 

 few short basal fulcra, increasing in length, occur at the origin of each fin, but 

 there appear to be no fringing fulcra. Each pectoral fin seems to have comprised 

 9 or 10 rays, while the pelvic fin has 8 or 9 rays, which are not much more than 

 half as long as the former. The dorsal fin occupies less than the middle third of 

 the back, and the length of its longest rays is somewhat less than the depth of the 

 trunk at their point of insertion. Three or four basal fulcra are distinguishable 

 at its origin. Its 17 supports are all long and stout, expanding at the upper end 

 where they articulate directly with the fin-rays, without the intercalation of any 

 other supports. The anal fin, best shown in the type specimen, is comparatively 

 small, but all its 8 supports are much elongated. The caudal fin, especially well 

 seen in PI. XIX, fig. 5, is very long and stout and un symmetrically rounded, as in 

 A in in. It is supported by about 14 thickened haemal arches at the upturned end 

 of the caudal region ; and slender basal fulcral scales are conspicuous both above 

 and below. 



The deeply-overlapping scales are uniform over the whole of the trunk, longer 

 than deep, and rounded at their free hinder border. The covered portion exhibits 

 only the fine concentric lines of growth, but the exposed portion is thickened and 

 finely pitted with markings which give it an irregularly reticulated appearance. 

 This structure is especially well seen in the type specimen (PI. XIX, fig. 6), in 



