VARIOUS SPECIES OF CTENODUS. G3 



outer slightly convex, the anterior slopes forward from the inner 

 margin, and the posterior is produced and rounded. The whole 

 surface is strongly and irregularly punctured. 



We have seen only one specimen of this fine large distinct spe- 

 cies ; it is a palatal tooth, and is in a veiy good state. It was 

 ohtained from the CoUingwood Main Pit, and was presented by 

 George Johnson, Esq., to the Newcastle Museum. It is readily 

 distinguished from its allies by the fewness of the ridges, by their 

 roundness and wide separation, as well as by their greater size 

 and general form. 



4. Ctenobus obliquus, n. sp. 



Tooth depressed, lanceolate, 1^ inches long, fths of an inch 

 broad ; the inner margin regularly and much arched, the outer 

 only slightly curved ; the surface with six or seven strong, com- 

 pressed, sharp-edged ridges, placed transversely in a somewhat 

 radiating manner towards the outer margin, where, being en- 

 larged, they are curved downwards and denticulated ; the ante- 

 I'ior ridges are very oblique, being much inclined forwards ; the 

 denticles or tubercles are much compressed in the direction of 

 the ridges, and are lancet-formed, with sharp points ; they are 

 coated with brilliant enamel in finely preserved specimens. The 

 above is the description of the palatal tooth ; the mandibular is 

 narrower than the former, and is broadest in front, tapering 

 pretty regularly to the posterior extremity ; the anterior ridge 

 is very wide, and much produced beyond the outer extremities 

 of the others, and they are all more curved downwards than 

 those of the palatal tooth. 



This is a very distinct form, and cannot be confounded with 

 any of the other species. We have collected between forty and 

 fifty specimens of it, most of which were procured from the Low- 

 Main shale at Newsham ; the rest are from Cramlington. Many 

 of them have the jawbone attached in a very perfect condition. 

 The palatal tooth is a little more than half the length of the 

 bone, the posterior extremity of which is much expanded and 



