1862.] HUXLEY — CAKBONIFEEOTJS LABTEINTHODONTS. 295 



two teeth. These teeth are situated at some distance (about 0*7 of 

 an inch) from the middle line, and pass outside the ramus of the 

 mandible. They are conical, and round in transverse section. 

 Neither is entire ; but the fragment on the right side is the longer 

 (0-2 inch), and is slightly curved, its convexity being directed for- 

 wards. The bases of the teeth are marked by strong longitudinal 

 grooves. 



The right ramus of the mandible is better shown than the left, 

 though both rami are more or less distorted and crushed. The 

 angular piece is large, and has the form and sculpture common 

 among Labyrinthodonts. 



Between the hinder parts of the rami of the mandible, but nearer 

 the left than the right, are two bony plates, having the form of right- 

 angled triangles, with their bases backwards, and their perpendica- 

 lars directed inwards, close to and parallel with one another. More 

 of the right plate is visible than of the left, and its outer angle is 

 seen to be produced into a process which is bent at a right angle 

 towards the dorsal side of the body. A coarse sculpture, consisting 

 of ridges which radiate fanwise from the outer angle of each plate 

 towards its inner edge, and anastomose, so as to leave elongated pits, 

 marks the surface of these plates. 



I conceive that these correspond with the lateral thoracic plates of 

 the Labyrinthodonts, thrown out of their proper places and approxi- 

 mated, so as to hide the anterior half of the lozenge-shaped median 

 plate, distinct traces of the posterior half of which plate appear to 

 me to be still visible. 



The ventral armour commences behind these thoracic plates, and 

 forms an oblong sheet of scales, about 4 inches broad and 17 inches 

 long, while each scale may measure half an inch long by '15 broad. 

 When the scales are well preserved and separately distinguishable, 

 they are seen to be somewhat oat-shaped, the outer end being much 

 more obtuse in some scales than in others. The scale is thick, and 

 rises to a sort of ridge in the middle. The inner end of its outer 

 face is commonly bevelled off, or grooved, so as to receive the outer 

 end of the next scale in front of and internal to it. The scales are 

 so arranged as to form oblique series, directed inwards and forwards, 

 and meeting in the middle line. 



Posteriorly (fig. 4) the scales seem to become longer, so as to assume 

 a bar-like character ; and at the extreme posterior end of the shield 

 there are two irregular, broad, flat plates, apparently bony, and each 

 rather more than half an inch wide. The structure of the fossil is 

 here, however, very obscure. 



Vertebral centra become distinctly visible on the left side of the 

 posterior third of the dermal shield. None of them are completely 

 exposed ; but, from what appears, tbey measure rather less than half an 

 inch antero-posteriorly, and a little more in a direction at right angles 

 to this. They are well ossified, slightly constricted in the middle, 

 and have either flat or biconcave articular ends — ^probably the latter. 

 The under surface, which is exposed, exhibits a median ridge and 

 two lateral depressions. 



