E. J). Wellhurn — On C<xlacanthus. 71 



clearly recognizable as of organic origin have a smooth surface. 

 But wherever or whatever the uuirkings perceived by Dr. Burckhardt 

 may be, their whole surface is adinittedly rough with " the coarse 

 grains of the sand," and they show no distinctive colour. 



" In size " these impressions are said by Professor Burckhardt to 

 "vary between o mm. and 3 cm. in diameter." Now Echinoderm. 

 plates or tests of this area must have had an appreciable thickness, 

 and this thickness would be manifest in their hollow casts, since the 

 rock has undergone no extrao-rdinary pressure. Therefore the spaces 

 should be visible in section wherever the rock is broken at a sharp 

 angle. But Dr. Burckhardt, who had a piece of the matrix specially 

 chipped off for examination, will doubtless admit tliat such is not 

 the case. 



If the matrix did contain impressions or moulds of Echinoderm 

 objects of the nature described by Professor Burckhardt, one would 

 certainly expect to find them lying roughly parallel to the plane of 

 stratification, and we are indeed told that these bodies are " all of 

 them lying in the same plane as the skeleton of Uyperodnpedony 

 But the skeleton in question is a large, irregular object, and the 

 exposed surfaces along which the matrix has been fractured ai-e not 

 in any one plane, but lie at various angles. There is no trace of 

 lamination, and if any objects ever did lie on the rough fracture- 

 surfaces, they must have been deposited in most irregular fashion, 

 and the sandy floor of the Triassic lagoon in which these reptile 

 skeletons lay undisturbed must have been unlike any sea-bed before 

 or since. But it is well known that the Elgin sandstones are quite 

 objectionably like dozens of other sandstones, and one cannot doubt 

 that were Professor Burckhardt to pursue the geological studies he 

 finds so attractive, he would discover equally clear or equally obscure 

 appearances, in many rocks besides those "fragments from the Maleri 

 deposits in India." 



We conclude, then, that the phenomena described by the learned 

 professor are mainly subjective, such objective basis as they possess 

 being furnished solely by the mechanical arrangement of sand-grains 

 and the natural irregularity of a broken surface. 



VIII.— On the Pectoral Fin of C(ELACAifTHU^, 

 By Edgau D. Wellburn, L.R.C.P., F.G.S., F.R.I. P.II., etc. 



AMONG the fossil fishes of the Talbragar Beds (Jurassic?) 

 described by Dr. A. Smith Woodward in a memoir of the 

 Geological Survey of New South Wales (1895), there is the ventral 

 portion of the abdominal region of a Coelacaiith fish, having one of 

 the pectoral fins well shown. The fin is shown in counterpart, and 

 is thus described : — " It exhibits, as usual, the characteristic ohtuso 

 lobation and the large fringe of articulated attenuated dermal rays, 

 and is unique in displaying some of the endoskeletal supporting 

 bones. These elements seem to have been well ossified, though 

 with persistent cartilage internally. At the base of the fin there 

 occurs a broken fragment of bone ' incapable of determination ; but 

 * My specimen would point to the fact that thi8 is a fragment of the clavicle. 



