BY PROFESSOR STEPPIENS, M.A., F.G.S. 1191 



owing to distortion. The head portion is nearly a right-angled 

 triangle, with * the perpendicular 4 mm. in length parallel to th e 

 spine, the base, about 5 mm., curving gradually to the rear, and 

 the hypotenuse, about 7 mm., bending towards it at an angle of 

 about 40.° The shafts then bend backward, so as to become more 

 or less parallel with the spine, for about 17 mm., and are con- 

 sequently in close juxtaposition. They then bend outward, about 

 10 mm., and so disappear. 



It is not easy to account for this double curvature of the ribs, 

 unless some such twisting of these curved bones has occurred as 

 might result from a forward shift of the upper surface of the fossil, 

 pushing the upper and proximal extremities forward, while the 

 distal and lower remained stationary, or moved in the opposite 

 direction. This would throw any vertical portions of the series 

 of ribs into the same straight line, and would, under the supposition 

 which follows, account for the close approximation of the shafts at 

 about half their length, while it would also, by the attendant 

 vertical pressure tend to make any forward processes spread 

 outwards. 



It may therefore be conjectured that each rib diverged from the 

 spine outwards and backwards, but nearly horizontally ; that it 

 then bent down nearly vertically towards the ventral aspect ; and 

 that finally it curved forwards towards the head. For under such 

 circumstances a gradual pressure from above and behind would 

 produce just such an arrangement as has been described. 



Certainly it may be doubted whether ribs of such a character 

 can be Labyrinthodont. Still, the tubular bones, the apparently 

 cartilaginous notochord and the dermal scutes — together with the 

 occurrence of No. 2 in the same beds — offer evidence which must 

 be lodged in the opposite scale. And I do not think anyone will 

 regard this fossil as the remains of a Fish. 



The preceding description and argument is based on the assump- 

 tion that we have the dorsal aspect presented to us. And the 

 -whole appearance of the fossil seems to warrant this assumption. 

 But there is a little difficulty in the way, since the remains of the 



