in the Neighbourhood of Edinburgh. 211 
In Mr Connex’s analysis, a little fluoride of calcium appears. 
The phosphate of magnesia, along with potash and soda, or 
the carbonate of soda, appear in very small proportions in both 
the fossil and recent animals. 
Gelatinous substance, with a very trifling quantity of fatty 
matter, amounting together to somewhat less than one-half of the 
materials contained in the scales of the recent Lepidosteus, has al- 
most entirely disappeared. In the fossil animal, Mr Conneiy 
could detect nothing more than a trace of animal matter. 
But the place of the animal substance has been supplied in 
the scales of the fossil fish, by nearly thirty-seven parts in a hun- 
dred of siliceous matter, in which is included a little combined 
water. These foreign ingredients have no doubt been derived 
from the matter in which the scales have been entombed. In 
the present instance, they evince the solubility of silex, under cer- 
tain circumstances, and its important geological character as a re- 
placing substance. 
From this interesting comparison, I now pass on to the round- 
ed scales of the Megalichthys. 
The Rounded Scales.—M. Acassiz has conceived that no doubt 
whatever can be supposed to hang over any of the bones which 
he has hitherto considered. Regarding one class of relics, how- 
ever, perhaps some little degree of obscurity may remain. The 
rounded scales of the Megalichthys are indicated by an internal 
eancellated, and by an external lamellar structure, as well as by 
an absence of ‘the shining enamel so distinctive of the angular 
scales. A representation is given of them in Plate VIII. Fig. 2. 
Some of the rounded scales appear to be finely fringed at 
their edges. (See Plate X. Fig. 2.) 
In Plate X. Fig. 3, a representation is given of these scales 
in astate of contiguity. M. Acassrz, from an examination of 
them, conceives that they are imbricated. 
The rounded scales are of various sizes. I have seen speci- 
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