256 RAMBLES OF A GEOLOGIST. 



to the waves on the one side as to the current on the other. 

 It is a true river bar, beaten in from its proper place in the 

 sea by the violence of the surf, and fairly stranded. Dr Emslie 

 obligingly submitted to my inspection his set of Gamrie fos- 

 sils, containing several good specimens of Pterichthys and 

 Coccosteus, undistinguishable, like those I had seen on the 

 previous day, in their state of keeping, and the character of 

 the nodular matrices in which they lie, from my old acquaint- 

 ance the Cephalaspians of Cromarty. The animal matter 

 which the bony plates and scales originally contained has been 

 converted, in both the Gamrie and Cromarty ichthyolites, into 

 a jet-black bitumen ; and in both, the inclosing nodules con- 

 sist of a smoke-coloured argillaceous limestone, which formed 

 around the organisms in a bed of stratified clay, and at once 

 exhibits, in consequence, the rectilinear lines of the stratifi- 

 cation, mechanical in their origin, and the radiating ones of 

 the sub-crystalline concretion, purely a trick of the chemistry 

 of the deposit. A Pterichthys in Dr Emslie's collection struck 

 me as different in its proportions from any I had previously 

 seen, though, from its state of rather imperfect preservation, 

 I hesitated to pronounce absolutely upon the fact. I cannot 

 now doubt, however, that it belonged to a species not figured 

 nor described at the time ; but which, under the name Pterick- 

 thys quadrate, forms in part the subject of a still unpub- 

 lished memoir, in which Sir Philip Egerton, our first British 

 authority on fossil fish, has done me the honour to associate 

 my humble name with his own ; and which will have the 

 effect of reducing to the ranks of the Pterichthyan genus the 

 supposed genera Pamphractus and Homothorax. A second 

 set of fossils, which Dr Emslie had derived from his tile-works 

 at Blackpots, proved, I found, identical with those of the 

 Eathie Lias. As this Banffshire deposit had formed a sub- 

 ject of considerable discussion and difference among geologists, 

 I was curious to examine it ; and the Doctor, though the day 



