Xliv. PREFATORY REMARKS 



inspecting the plate which is there given, and which forms, 

 as nearly as may be, a restoration of the Cephalaspis. The 

 only part which seems at all doubtful is the tail I have 

 been shown the specimen from which the engraving was 

 taken by the gentleman in whose possession it is, — Mr Pow- 

 rie of Reswallie, one of the best collectors and geologists in 

 Forfarshire. The indications of a large and powerful tail 

 are unmistakeable ; but most unfortunately the quarryman 

 who disinterred the slab in which this fine specimen was 

 found, and which showed at first only the foremost part of 

 the skull, did not make sufficient allowance for the size of the 

 animal, when reducing the slab to a portable size, and a great 

 part of the tail was consequently cut away. The plates of the 

 head, the pectoral fins, and the eye-orbits, are all as distinct 

 as if freshly cut by the tool of the engraver out of wood or 

 stone. In a second specimen, the capsules of the eyes are 

 preserved. The whole body in the larger specimen is closely 

 covered with apparently very strong scales of a rhomboidal 

 form. Here, then, there is no longer need of guess-work 

 from spines, teeth, and pieces of shagreen, but an absolute 

 form, which the most unpractised eye may discern to be no 

 foetus or half-developed crustacean, but a fish in all respects 

 aa perfectly organized after its kind as any fish — the lepi- 

 dosteus, for example — of the present day. Nor is it among 

 the lower orders of existing fishes that the first comparative 

 anatomists seek its analogues. Both Professor Owen and 

 Professor Huxley, though differing in their ideas of classifi- 

 cation, find these in the Siluroids, — an order of teleostean oi 

 bony fishes. The first of those great authorities, follow- 

 ing Agassiz, retains the ganoid order intact, as adopted by 



