CCELODUS. 67 



hindmost, which displays its median constriction, raised ends, and the trans- 

 versely elongated apical pit with a crennlated anterior rim. To the left the lateral 

 teeth are covered by hard matrix, but on the right side (fig. 6 a) both series are 

 well seen, with traces of small intercalated teeth in front ; all probably had an 

 apical pit, but they are so much worn that only the hindmost tooth of the outer 

 series retains the crennlated rim. The teeth in smaller examples of the vomerine 

 dentition have a larger and deeper apical pit with crennlated margin ; but the 

 specimens are usually so much worn by mastication and accidentally flaked in the 

 fossils, that this feature is often obscured. In many cases the wearing of the teeth 

 reaches the pulp-cavity, and in one specimen figured by Agassiz (torn, cit., pi. lxxii a, 

 fig. 13) only the broken bases of insertion are seen on the bone. 



In specimens of the adult splenial dentition, as in one figured by Agassiz (torn. 

 cif., pi. lxxii a, fig. 14) and in the original of PL XV, fig. 7, the anterior tapering- 

 end is usually broken away ; but some of the immature stages represented by this 

 end are shown in PI. XV, figs. 8 — 11. The smallest of these specimens (fig. 9) was 

 wrongly referred by Agassiz [Joe. cit.) to the upper jaw of Gyrodus, under the name 

 of G. mantellii. It is a left splenial bone, of which the inner margin is recognisable 

 in the matrix, and it exhibits the three characteristic regular rows of teeth, each 

 with a large apical pit which has been more or less reduced by wear. A larger 

 left splenial (fig. 10) bears teeth which are not only much worn but also a little 

 flaked. The third small splenial dentition (fig. 8) has already been figured by 

 Agassiz (torn, cit., pi. lxxii a, fig. 11), and is interesting as still retaining the 

 crenulations round the margin of the apical pit in the hinder teeth. The fourth 

 specimen (fig. 11), which is detached from the matrix, shows well (fig. 11 a) the 

 depth of the groove in the dental armature formed by the lateral teeth, and the 

 extreme wear in the front part of this groove. Several small examples of the denti- 

 tion from the Wealden (presumably Weald Clay) of Sevenoaks, Kent, in the 

 Museum of Practical Geology, are interesting both for the fine unworn condition 

 of many of the teeth and for the irregular subdivision of some others. 



Horizons and Localities. — Wealden : Tilgate Forest, Tunbridge Wells, and 

 Hastings, Sussex ; Atherfield, Isle of Wight ; Sevenoaks, Kent. Lower Wealden 

 or Upper Purbeck : Netherfield, Sussex. 



2. Ccelodus multidens, sp. nov. Plate XV, figs. 12, 13. 



Type. — Splenial bone ; Museum of Practical Geology, London. 



Specific Characters. — -Initial anterior end of splenial bone wider than in 

 C. inantelli, covered with an irregular group of smooth rounded teeth, each with 

 an apical pit; mature splenial teeth almost as in G. mantelli, but apical pit 

 apparently shallower. 



