CCELODTTS. 69 



obvious. The anterior as well as the posterior face (fig. 15 a.) exhibits traces of 

 concentric lines of growth across the characteristic wrinkled ornament, and the 

 peripheral nature of the root is clear (figs. 15 a, b). A smaller specimen (fig. L6) 

 shows well the remnant of the apical pit as a slight fissure from which the coronal 

 wrinkles diverge. 



The lateral teeth have not been identified with certainty, but the low-crowned 

 ovoid specimen represented in PL XV, fig. 17, may be one of them. The peripheral 

 ornament of the crown resembles that of the principal teeth of this species, but 

 that of the middle of the crown is a coarse irregular tuberculation. Among other 

 teeth that are evidently Pycnodont, the small elongated specimen with a high crown 

 shown in PI. XV, fig. 18, may also belong to one of the lateral series of 0. lunula. 



A microscopical section made from one of the principal teeth exhibits the 

 typical Pycnodont structure, densely arranged minute tubuli traversing the dentine 

 from the pulp-cavity direct to the superficial ganodentine. 



Horizon and Localities. — Wealden : Tilo-ate Forest; neighbourhood of Hastings 

 (Wadhurst Clay and Ashdown Sands) ; Telham, near Battle. 



4. Coelodus laevidens, sp. nov. Plate XV, figs. 19, 20. 



Type. — Splenial bone ; British Museum. 



Specific Characters. — A small species with splenial dentition usually not more 

 than 2 - 5 cm. in length. Teeth of principal series on the splenial bone about twice 

 as broad as long, scarcely tapering inwards and not much (if at all) raised at the 

 outer end ; surface smooth and apical pit absent or very shallow ; the width 

 equalling or somewhat exceeding that of the two flanking series. Teeth of inner 

 flanking series also about twice as broad as long, only slightly raised at the inner 

 end, smooth but with a deeper apical pit. Teeth of outer flanking series smaller, 

 less transversely elongated, smooth but with shallow apical pit. 



Description of Specimens. — The type specimen (PL XV, fig. 19) is the hinder 

 part of a right splenial, of which the hindmost principal tooth is scarcely worn but 

 still shows no more than the feeblest trace of an apical pit. The two hindmost 

 flanking teeth, though pitted, are not crimped. The younger specimen of the left 

 splenial shown in PL XV, tig, 20, is altogether similar, and bears the three rows 

 of teeth in regular series to the anterior apex. Though in most respects resembling 

 the corresponding dentition of Coelodus mantelli, the absence of a well-defined 

 apical pit in the principal teeth and the shape of the inner flanking teeth are 

 characters suggesting that this form of jaw belongs to a distinct species. 



A vomerine dentition closely similar to that of C. mantelli is known from the 

 same horizon as the splenial just described, and probably belongs to this species. 



Horizon and Locality. — -Middle Purbeck Beds : Swanage, Dorset. 



