94 ME. E. T. NEWTON ON A MEGALOSATJKOID J AAV [Feb. I 899, 



extent of the serration on the anterior border of the teeth has 

 been thought to be some guide to their generic affinities ; but the 

 variations in this respect to be seen among the species included in 

 the genus Megalosaurus show that this character can hardly be 

 relied upon for more than specific distinction. Megalosaurus Buck- 

 landi, from the Lower Oolites, has the serration of the anterior 

 border of the teeth limited to the apical third of the enamelled 

 crown ; in M. insignis, from the Upper Oolites, it extends for two- 

 thirds the length of the crown ; and in M. suptrhus, from the 

 Cretaceous rocks of France, it is apparently coextensive with the 

 crown. 



A similar variation is found among the Megalosauroid teeth 

 occurring in Triassic rocks ; but specimens from those strata have 

 been placed in several genera, as already mentioned. Of these only 

 Zanclodon^ Palceosaurus, Cladyodoti, Avcdonia, and Picrodon need 

 be again discussed, and some at least of these might with advantage 

 be included in the genus Zanclodon. The teeth of Zandodon 

 suevicus, with which may be included the Warwickshire tooth 

 described by Huxley under the name of Teratosaunis, are more 

 compressed, and have the anterior serration extending farther down 

 the crown than in our Bridgend specimen. Palceosaurus cylin- 

 drodon has the teeth more cylindrical than in the present fossil, 

 although the serration may have been much the same. The tooth 

 named Avalonia Sanfordi (with which I should include Picrodon 

 Herveyi) has a close resemblance to those of the Bridgend reptile, 

 but the imperfection of the Wedmore specimens prevents a satis- 

 factory comparison of their serration, and these teeth are less curved 

 than are those of the Bridgend jaw. 



Inasmuch as it does not appear to me that the generic distinct- 

 ness of Avalonia is well established, I am constrained to refer the 

 Bridgend reptile to the genus Zandodon ; and as it differs from any 

 recorded species, this Welsh Dinosaur may appropriately be named 

 Zandodon camhrensis. 



EXPLANATION OF PLATE X. 



Zandodon camhreoisis, sp. nov. 



[From Penartli Beds (Ehaetic?), Stormy Down, Bridgend, Grlaniorgansbire ; 

 obtained by Mr. John David, of Porthcawl, and presented to the Mu.seuin of 

 Practical Geology, Jermyn Street. The specimen being merely a hollow mould, 

 the figures have been drawn from casts made in gutta percha.] 



Fig. 1. Inner side of the left dentary bone. About ^ nat. size. The points of 

 young teeth are shown at the bases of a & 6. 



2. Outer surface of the anterior portion of the same dentary bone. 



3. Portion of bone with two teeth, seen from the inner side. Nat. size. 



To show the serration of the teeth. 



4. Tooth a of fig. 1. Nat. size. To show the new tooth appearing in a pit 



at the base. 



