288 RAMBLES OF A GEOLOGIST. 



it abruptly terminates a little short of the termination of the 

 plate, exactly as in the dorsal plate of Coccosteus, which sunk 

 its central ridge deep into the back of the animal. The point 

 of resemblance to be mainly noticed, however, is the contrast 

 furnished by the powerful armature of the head and back, 

 with the unprotected nakedness of the posterior portions of 

 the creature ; a point specially noticeable in the Coccosteus, 

 and apparent also, though in a lesser degree, in some of the 

 other genera of the Old Red, such as the Pterichthyes and 

 Asterolepides. From the snout of the Coccosteus down to the 

 posterior termination of the dorsal plate, the creature was 

 cased in strong armour, the plates of which remain as freshly 

 preserved in the ancient rocks of the country as those of the 

 Pimelodi of the Ganges on the shelves of the Elgin Museum 

 but from the pointed termination of the plate immediately 

 over the dorsal fin, to the tail, comprising more than one 

 half the entire length of the animal, all seems to have been 

 exposed, without the protection of even a scale, and there 

 survives in the better specimens only the internal skeleton 

 of the fish and the ray-bones of the fins. It was armed, like 

 a French dragoon, with a strong helmet and a short cuirass ; 

 and so we find its remains in the state in which those of some 

 of the soldiers of Napoleon's old guard, that had been com- 

 mitted unstripped to the earth, may be dug up in the future 

 on the fatal field of Borodino, or along the banks of the 

 Dwina or the Wap. The cuirass lies still attached to the 

 helmet, but we find only the naked skeleton attached to the 

 cuirass. The Pterichthys to its strong helmet and cuirass 

 added a posterior armature of comparatively feeble scales, as 

 if, while its upper parts were shielded with plate armour, a 

 lighter covering of ring or scale armour sufficed for the less 

 vital parts beneath. In the Asterolepis the arrangement was 

 somewhat similar, save that the plated cuirass was wanting : 

 it was a strongly helmed warrior in slight scale armour ; 



