208 Dr Hrezert on the Limestone of Burdiehouse, 
found upon the palatine bones; but in other species of the same 
animal, they rather occur upon the margin of the maxillary bone, 
and more especially 1 in their anterior part. 
And again, in the new genus of Macropoma (Agass.) of 
which Mr Mawreti’s Amia Lewésiensis is considered as the 
type, and of which M. Acassrz professes he is not acquainted 
with any living species, a similar alternation was observed. Teeth 
of very different sizes occurred, always smaller on the edge of the 
jaw bones, and proportionally very large upon the internal bones 
of the mouth, so that it would have been difficult to conceive 
that the fragments shewing a series of palatine teeth, or those 
shewing a series of maxillary teeth, had belonged to the same 
fish, if they had not been found united in other examples. 
These were the instances of analogy by which M. Agassiz, in 
the first instance, proposed to explain the difference in the size 
of the teeth which are distributed along the jaws of the Mega- 
lichthys, and from which he inferred that a similar disposition 
might prevail in the Burdiehouse animal. His anticipation, as 
I have remarked, was singularly confirmed. 
It has been at length shewn that in the Megalichthys very 
large teeth have coexisted with very small ones; but as they se- 
verally exceed so much in magnitude those of the recent Lepi- 
dosteus, our admiration is greatly excited in contemplating the 
enormous sauroid fish of a former world. 
The larger teeth of Plate IX. fig. 2 and 10, have a breadth 
at their base of 14 to 2 inches, and a length of nearly 4 inches 
After having explained the teeth and their distribution, I now 
proceed to the scales of the Megalichthys. 
One description of scales exhibits a coating of enamel of a nut- 
brown colour, and often of the most brilliant lustre imaginable. 
These scales are of various forms, as may be seen in Plate VIII 
fig. 3 to 5, and Plate XI. fig. 2 to 8. They are generally angular. 
A curious character is the punctured surface, which many of these 
2 
