162 Mr. T. Attheyt'^ Anthracosaums Russelli. 



are deviated to the left and at right angles to the others. The 

 upper end has been broken off obliquely, together with the 

 bones on which it rests. It is 4 inches in length as it lies ; 

 the lower end strongly resembles the lower end of a femur, 

 and has been compressed from side to side. The shaft has 

 been longitudinally broken in upon its cavity, and is therefore 

 irregular ; and the upper end or head is entirely Avanting. 



Plate XI. fig. 1 is a transverse section of a maxillary tooth 

 of Anthracosaurus^ from a specimen in my collection, other 

 than that figured in the former Plates. It is made at a line 

 a little below the apex and above the top of the pulp-cavity. 

 It is rather more elliptical than circular in outline, having two 

 slight ridges corresponding to the ends of the long diameter ; 

 these ridges show the position of the two cutting-edges of the 

 tooth. The dentine pervades the whole area within the enamel, 

 a thickish layer of which encloses the dentine. It does not 

 appear that this part of the tooth has undergone any flattening 

 or other injury. 



Fig. 2 is a transverse section a little below fig. 1 and just 

 below the top of the pulp-cavity. The outlines of the tooth 

 and of the pulp-cavity are oval, that of the former broadly so. 

 No coating of enamel is visible, except at one part, where a por- 

 tion of matrix is adherent to the tooth ; a stellate appearance, 

 which strikes the eye at once, arises from the arrangement of 

 fifteen fusiform bodies of light-coloured dentine around the 

 pulp-cavity, radiating from it to the circumference; the internal 

 apices project slightly into the pulp-cavity and give to its 

 outline an undulating appearance ; their external and more 

 pointed apices reach quite to the circumference of the tooth, 

 where a nan-ow peripheral band passes from the outer margin 

 of the tooth directly into each of them, extending for a short 

 distance towards the pulp-cavity. The dentinal tubes of the 

 fusiform bodies all pass into this narrow infolded band, which 

 is dark-coloured, not light as in Loxomma. The light-coloured 

 fusiform bodies appear as if imbedded in dentine of a dark 

 colour, which is owing to the tubules of it being black ; and this 

 dark dentine is broadest at the periphery of the tooth, in each 

 interval between the spindles. The dentinal tubes in this 

 dark part pass from its middle, radiating outwards towards the 

 periphery of the tooth. 



Fig. 3. is a transverse section a little below fig. 2, but still 

 above the termination of the radiations of the pulp-cavity. Its 

 fonn is more elliptical than that of the former sections; the same 

 radiating fusiform bodies of light-coloured dentine, but of a 

 larger size, are seen, encroaching upon the external darker den- 

 tine ; the narrow infolded peripheral band runs inwards here 



