ON A LABYRINTHODONT AMPHIBIAN. 211 



concerned — though probably they also comprise the epiotics ; 

 for it can scarcely be supposed that these latter bones lie within 

 the raised boundary lines which we assume to be those of the 

 occipitals. And yet, from analogy, it might be thought that the 

 inner cornua formed the posterior extremities of the epiotics. 

 In front of the lateral expansions, and external to the frontals 

 and parietals, the ridges on the surface probably indicate the 

 presence of the several component bones of these parts ; but it 

 is imposible to determine with precision their limits and exact 

 configuration. 



The posterior margin of each lateral expansion extends in a 

 straight line outwards and backwards from the base of the occi- 

 pital horn for seven-tenths of an inch to the external horn, which 

 projects backwards with a slight inclination outwards, and is 

 four-tenths of an inch long and one-fourth of an inch wide at the 

 base ; the surface is rough, like that of the inner horns, and is 

 carinated longitudinally above and below, so that it presents four 

 irregular facets. Of the lateral margins only the posterior por- 

 tion of the left side is perfect, and this turns suddenly forward 

 from the base of the horn in a slightly convex line for nine-tenths 

 of an inch ; it then bends rather abruptly forwards and inwards, 

 and extends in an outward curved line for six-tenths of an inch 

 further, at which point the margin of this side is broken away in 

 an inward sloping direction to the anterior extremity of the skull. 

 At the right side in front the lateral margin is folded inwards, 

 and is otherwise injured for nearly tAvo-thirds of its length ; the 

 posterior third is almost perfect, but the lateral horn is broken 

 off. 



The surface of the skull is in a very good state of preservation, 

 and is sculptured in a very peculiar manner, long linear ridges 

 being the most conspicuous feature. As already stated, such 

 ridges define the boundaries of the coronal bones ; those of the 

 occiput are very strong, and, together with the lateral ridges of 

 the parietals, form along the sides of the central portion of the 

 skull two nearly parallel lines enclosing the occipitals and parie- 

 tals, each of which is rectangular in form. Other lines pass 

 diagonally backwards in a radiating manner from the junction of 



