THE OLD RED SANDSTONE. 143 
pis Lyellii. The crescent-shaped horns were wanting, 
and the outline a little obscure; but the eyes were better 
marked than in almost any other specimen I have yet 
seen, and the circular star-like tubercles which roughen 
the large occipital buckler, to which the creature owes its 
name, were tolerably well defined. I was shown the head 
of another individual of the same species in the centre of a 
large slab, and nothing could be more entire than the outline. 
The osseous plate still retained the original brownish-white 
hue of the bone, and its radiated porous texture; and the 
sharp crescent-shaped horns were as sharply defined as dur- 
ing the lifetime of the strangely organized creature which 
they had defended. In both specimens the thin angular body 
was wanting. Like almost all the other fish of the Old 
Red Sandstone, the bony skeleton of the Cephalaspis was 
external —as much so as the shell of the crab or lobster: it 
presented at all points an armor of bone, as complete as if 
it had been carved by the ivory-turner out of a solid block; 
while the internal skeleton, which in every instance has dis- 
appeared, seems to have been composed of cartilage. I 
have compared its general appearance to_a saddler’s cutting- 
knife ;—I should, perhaps, have said a saddler’s cutting- 
knife divested of the wooden handle — the broad, bony head 
representing the blade, and the thin angular body the iron stem 
usually fixed in the wood. No existence of the present crea- 
tion at all resembles the Cephalaspis. Were we introduced 
to the living creatures which now inhabit the oceans and riv- 
ers of Mars and Venus, we could find nothing among ther. 
more strange in appearance, or more unlike our living 
acquaintances of the friths and streams than the Cephalas- 
pides of Carmylie. (See Note F.) 
I observed, besides, in the quarry, remains of the huge 
