334 MESSRS. HANCOCK AND ATTHEY 



Ob another small slab recently obtained there is a fine speci- 

 men of a second lateral tooth associated with a secondary tooth. 



From the above it appears that there is evidence enough to 

 shovs^ that in Climaxodus, as in Janassa, the teeth are placed in 

 transverse rows of seven teeth each, one being symmetrical and 

 central, and six lateral, three on each side, the extreme lateral 

 tooth on either side being Petalodontoid in form, that there are 

 more rows than one, and that they are placed in both upper and 

 under jaws. In fact it is quite evident, not only that the teeth 

 in Climaxodus agree in external character with those in Janassa, 

 but that they also agree with them in the mode of arrangement. 



The minute structure of the teeth in the two so-called genera 

 is very similar. In both the centre of the tooth is composed of 

 osteo-dentine, having branched anastomosing medullary canals, 

 which are for the most part an-anged lengthwise, and give off 

 from their sides rather coarse tubules into the surrounding mat- 

 ter. The canals likewise send off comparatively small branches, 

 which subdivide dichotomously as they approach the periphery 

 of the tooth. Here many of them abut perpendicularly to the 

 surface. The walls of these small branches assume the character 

 of dentine, and the interstices between them are filled up with 

 opaque white matter — probably cement ; so that, by the unequal 

 wear of these peripheral components, the surface of the tooth is 

 always kept rough, having the granular and punctate appearance 

 before spoken of. When quite fresh, there is a thin film of ena- 

 mel covering the surface ; but this seems to disappear rapidly 

 with the use of the tooth. 



The teeth of both Climaxodus and Janassa agree with the above 

 general description ; but in the latter the material appears more 

 dense, and the cement is in greater abundance and is distributed 

 more regularly than it is in Climaxodus, consequently it is found 

 to assume a pretty regular reticulated appearance on the surface 

 when a little worn down. 



The generic identity, then, of Climaxodus and Janassa seems 

 pretty certain ; and as the latter was established many years 

 (1882) before the former (1848), the genus Climaxodus must 



