116 AUTUMNS ON THE SPEY. 



of being black, like the ichthyolites of Cromarty. 

 The specimen before me measured about four 

 inches and a half in length, and four inches and 

 a quarter from point to point of its wings exclu- 

 sive of the matrix. These are supposed by Agas- 

 siz not to be organs of locomotion, but a defence 

 against its enemies, on the approach of whom it 

 suddenly extended them, as the perch erects its 

 dorsal fin, or a stickleback its spines, for a similar 

 purpose. With the exception of the difference in 

 colour to which I have alluded, and a more perfect 

 head, the following brief quotation from Miller 

 will give you a familiar notion of the profile of the 

 pterichthys of Tynet burn. " Imagine the figure 

 of a man rudely drawn in black on a grey ground : 

 the head cut off by the shoulders ; the arms 

 spread at full, as in the attitude of swimming ; 

 the body rather long than otherwise, and narrow- 

 ing from the chest downwards ; one of the legs 

 cut away at the hip-joint, and the other, as if to 

 preserve the balance, placed directly under the 

 centre of the figure, which it seems to support. 

 Such, at first glance, is the appearance of the 

 fossil." 



There are portions of another fish, nearly allied 

 to the pterichthys, in this collection the coccos- 

 teus, or berry-bone. It was covered with an 



