in the Neighbourhood of Edinburgh. 21 1 



In Mr Connell'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 Connell 

 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. Agassiz 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 

 cancellated, 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 a state of contiguity. M. Agassiz, from an examination of 

 them, conceives that they are imbricated. 



The rounded scales are of various sizes. I have seen speci- 



Dd2 



