THE OLD RED SANDSTONE. 127 
handle an angular, instead of a rounded shape, and to press 
together the pointed horns of the crescent, till they incline 
towards each other, and the convex, or sharpened edge, is 
elongated into a semi-ellipse, cut in the line of its shortest 
diameter, in order to produce the complete form of the Ceph- 
alaspis. The head, compared with the body, was of great 
size — comprising fully one third the creature’s entire length. 
In the centre, and placed closely together, as in many of the 
flat fish, were the eyes. Some of the specimens show two 
dorsals, and an anal and caudal fin. The thin and angular 
body presents a jointed appearance, somewhat like that of a 
lobster or trilobite. Like the bodies of most of the ichthyolites 
of the system, it was covered with variously formed scales of 
bone ; the creature’s head was cased in strong plates of the 
same material, the whole upper side lying under one huge 
buckler — and hence the name Cephalaspis, or buckler-head. 
In proportion to its strength and size, it seems to have been 
amply furnished with weapons of defence. Such was the 
strength and massiveness of its covering, that its remains are 
found comparatively entire in arenaceous rocks impregnated 
with iron, in which few other fossils could have survived, 
Its various species, as they occur in the Welsh and English 
Cornstones, says Mr. Murchison, seem “not to have been 
suddenly killed and entombed, but to have been long exposed 
to submarine agencies, such as the attacks of animals, cur- 
rents, concretionary action,” &c.; and yet, ‘though much 
dismembered, the geologist has little difficulty in recognizing 
even the smallest portions of them.” Nor does it seem to 
have been quite unfurnished with offensive weapons. The 
sword-fish, with its strong and pointed spear, has been known 
to perforate the oaken ribs of the firmest built vessels ; and 
poised and directed by its lesser fins, and impelled by its 
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