1190 ON SOME ADDITIONAL LABYRINTHODONT FOSSILS, N. S. WALES, 



skin, which clothed it, and in the cartilaginous state of the 

 skeleton, beyond which few of them advanced. For these 

 characters all harmonise with the object in view. Perhaps one 

 might even add, as a concomitant variation towards the same end, 

 the strangely complicated structure, trussed, braced, and com- 

 pensated, of the Labyrinthodont tooth. 



The second specimen which is exhibited this evening is from 

 Bowral, from the Wianamatta Shale. This fragment is so 

 impregnated with iron as to make a good ore. It appears to be 

 a portion of a maxillary bone, is about 2 inches in length, and 

 bears the remains of five teeth much weathered and broken. They 

 were set very close to one another, and may have been about three- 

 quarters of an inch in length, with a diameter at the base of about 

 •37 inch. Their material, like that of the bone, has been mainly 

 replaced by transparent calcite. The bone exhibits parallel ridges, 

 and is about an inch in width. 



The last specimen of the three is also from Bowral, in a dark 

 indurated shale belonging to the Wianamatta series. It contains 

 portions of 11 vertebra?, with the ribs of the left side. The spinal 

 column is marked by a flattened ridge, well-defined at the edges, 

 about 2 mm. in width, and probably representing the series of 

 neural spines. Some obscure undulations from front to rear may 

 indicate joints. 



About the same distance to the left are seen the proximal ends 

 of the ribs, not less than 4 mm. in width, though perhaps expanded 

 by pressure. The ribs were hoi low, and are now principally filled 

 with calcite, a narrow streak of which is also visible along the 

 spine. Miall on Hijfonomus (Report 1874, p. 173) describes 

 similar ribs, and gives a note from Owen upon them, in which it 

 is shown that the cavity was not properly a medullary one, but 

 was posthumous, and due to the solution of the primitive cartila- 

 ginous mould of the boDe, which had remained unchanged by 

 ossification in the living species. He concludes that these bones 

 were originally solid, and composed, as in most amphibians, of an 

 osseous crust enclosing cartilage. Their shape is peculiar, probably 



