RAMBLES OP A GEOLOGIST. 427 



very intelligent palaeontologists, to mark the place and cha- 

 racter of the fossil, that they might be able to point it out 

 to geological visitors in the future, or, if they preferred re- 

 moving it to their town Museum, to indicate to them the 

 stratum in which it had lain. For the present I merely re- 

 quest the reader to mark, in the passing, that the most an- 

 cient organic remain yet found in the Old Red of this part 

 of the country, nay, judging from its place, one of the most 

 ancient yet found in Scotland, so far as I know, absolutely 

 the most ancient, belonged to a ganoid as bulky as a large 

 porpoise, and which, as shown by its teeth and jaws, possess- 

 ed that peculiar organization which characterized the reptile 

 fish of the Upper Devonian and Carboniferous periods. As 

 there are, however, no calculations more doubtful or more to 

 be suspected than those on which the size and bulk of the 

 extinct animals are determined from some surviving frag- 

 ment of their remains, plate or bone, I must attempt lay- 

 ing before the scientific reader at least a portion of the data 

 on which I found. 



This figure represents not 

 inadequately one of the most 

 characteristic plates of the 

 Asterolepis. A very consider- 

 able fragment of what seems 

 to be the same plate has been 

 figured by Agassiz, from a cast of one of the huge specimens 

 of Professor Asmus (" Old Red," Table 32, Fig. 13) ; but as 

 no evidence regarding its true place had turned up at the 

 time, it was supposed by the naturalist to form part of the 

 opercular covering of the animal. It belonged, however, to 

 a different portion of the head. In almost all the fish that 

 appear at our tables the space which occurs within the arched 

 sweep of the lower jaws is mainly occupied by a complicated 

 osseous mechanism, known to anatomists as the hyoid bone 



