348 MR. A. SMITH WOODWARD ON N liW FISHES [Apr. 1.5, 



superior border exhibit a deep, uarrow depression overlapped by two 

 supra-muxillary bones {smx.). Of the latter the hindermost is 

 irregularly triangular, pointed behind, deepest in front, with a sharp 

 re-entering angle on the anterior border, and a long antero-superior 

 process ; the second element is also triangular, but much elongated, 

 its narrow base fitting into the re-entering angle just mentioned, and 

 its tapering apex directed forwards. In the mandible, the articular 

 bone (ar.) is laterally compressed, abruptly truncated behind, narrow 

 beneath the socket for the condyle, and much expanded forwards in 

 the form of an elevated triangular plate. The dentary (d.) is long, 

 thin and deep, abruptly truncated at the symphysis, but too much 

 crushed to exhibit all the details of form. The mandibular suspen- 

 sorium is somewhat inclined forwards, and the dentary symphysis 

 evidently projects in advance of the premaxillee. Of cheek-plates 

 and circumorbitals almost all traces are lost, but fragments of a thin 

 lamina of bone, above and exterior to the metapterygoid, may 

 probably be assigned to this category; they are marked by somewhat 

 radiating ridges. Of the hyoid arch and its appendages, the right 

 ceratohyal, with the distal end of the epihyal in position, is exhibited 

 in the small Purbeck fossil described by A^assiz, and there seems to 

 be evidence of small, slender, widely spaced branchiostegal rays. The 

 opeiculum and suboperculum are not distinctly recognizable in any 

 specimen ; but the preopercidum (Plate XXIX. fig. 2) is a charac- 

 teristic element. This bone is of considerable size, narrow and 

 deep, with a broad, much thickened anterior border ; its lower limb 

 is relatively large, meeting the upper limb in a sharp angulation ; and 

 the hinder expansion of the upper limb is almost smooth, while that 

 of the lower limb is separated from this by a transverse ridge and is 

 itself marked by three or four rounded, parallel, or somewhat 

 divergent ridges. 



Dentition. — The oral margin of the maxilla is thickened, rounded, 

 and regularly reticulated in such a manner as to suggest the original 

 presence of a uniform cluster of very small teeth. None of these 

 are preserved ; and the teeth of the mandible are also not shown, its 

 dentigerous border being obscured by pyritons matrix and the over- 

 lap of the maxillae. In the small Purbeck fossil, however, the 

 symphysial end of the right dentary is well exhibited (Plate XXIX. 

 fig. 1). Here are preserved a few small, stout, conical teeth, which 

 seem to have formed jiart of an irregular spaced series, around and 

 between which were still more minute teeth. 



Branchial Arches. — In the postero-inferior region of the type speci- 

 men, a short vertical series of small, horizontally directed, thick rods 

 is conspicuous (ff.r.), though very imperfectly preserved ; and the 

 ap])earance of these fragments is at tirst suggestive of the base of a 

 powerful pectoral fin. The supposed Lepidotus tninor of Agassiz, 

 however, explains that the structures in question are referable to the 

 branchial apparatus ; and in the last-mentioned fossil one of the 

 arches is tolerably well displayed from the outer aspect (Plate 

 XXVIII. fig. 2). A most singular feature is thus made known, the 

 arch being provided with a close series of enormous bony gill- 



