CaGiLODUS. 165 
posteriorly elongated and comprised in the outermost series. Nearly all the teeth 
indented, the smaller ones having the pit especially conspicuous and surrounded 
with a crenulated margin. 
Description of Specimen.—This species 1s still known only by the type specimen, 
which is important as exhibiting some features in the cranial osteology of the fish. 
The skull is much elongated, and the snout must have been acutely pointed. The 
mesethmoid forms a stout median septum in the rostral region, and unites in an 
extended suture with the vomer below. At the hinder end of the vomer, a short 
distance beyond its dentition, the pterygo-quadrate palatine arcade is shown as i 
continuous, inwardly curved thin plate of bone fused with the base of the skull, 
perhaps with the edge of the parasphenoid. It is toothless. A thin median keel 
extends along the lower face of the parasphenoid. The structure of the mandible 
(Pl. XXXIV, fig. 5) is not clear, but its articular element exhibits a very deep 
undulating facette (art.), and on the splenial (spl.) the teeth are restricted to a 
surface considerably within the external margin of the bone. 
The vomerine teeth (fig. 5a), as mentioned in the specific diagnosis, are 
remarkably irregular in size and arrangement. They appear to begin as three 
longitudinal series, but these soon become indefinite; and it is curious that the 
largest teeth are not in the middle, but in the marginal row. ‘The _ splenial 
dentition (fig. 5) is noteworthy for the very shght differentiation of a principal 
series of teeth. 
Horizon and Locality —Zone of Holaster subglobosus: Glynde, Sussex. 
Genus COHLODUS, Heckel. 
Celodus, J. J. Heckel, Denkschr. k. Akad. Wiss., math.-naturw. Cl., vol. xi, 1856, p. 202. 
Glossodus, O. G. Costa (non M‘Coy, 1848), Atti Accad, Pontan., vol. vii, 1853, p. 26. 
Cosmodus, H. E. Sauvage, Bull. Soe. Sci. Nat. Yonne, vol. xxxiu, pt. 1, 1879, p. 48. 
Generic Oharacters—Trunk very deeply fusiform, with slender abbreviated 
caudal pedicle. Head and opercular bones externally rugose and punctate ; most 
of the teeth exhibiting an apical indent with crenulated border; oral surface of 
vomer strongly convex from side to side, with teeth in five longitudinal series ; 
splenial dentition comprising three series of teeth with long axes directly trans- 
verse, sometimes supplemented within by a small row, and all the outer teeth 
showing frequent tendency to irregular subdivision. Neural and hemal arches 
of axial skeleton of trunk not expanding sufficiently to encircle the notochord. 
Fin-rays robust, closely articulated, and much divided distally. Pelvic fins present ; 
dorsal and anal fins high and acuminate in front, low and fringe-like behind, the 
former occupying at least the hinder half of the back and the latter somewhat 
shorter, arising more posteriorly; caudal fin deeply forked, with a convexity in 
