THE OLD RED SANDSTONE. 75d 
The Glyptolepis, or carved scale, may be -'egarded as the 
representative of a family of the Lower Old Red Sandstone, 
which, differing very materially from the genera described, 
had yet many traits in common with them, such as the bare, 
_ bony skull, the bony scales, the naked rays, and the unequally 
sided condition of tail. The fins, which were of considera- 
ble length in proportion to their breadth of base, and present 
in some of the specimens a pendulous-like appearance, clus- 
ter thick together towards the creature’s lower extremities, 
leaving the upper portion bare. There are two dorsals 
placed as in the Dipterus and Diplopterus — the anterior di- 
rectly opposite the ventral fin, the posterior directly opposite 
the anal. The tail is long and spreading ;—the rays, long 
and numerously articulated, are comparatively stout at their 
base, and slender as hairs where they terminate. The 
shoulder-bones are of huge dimensions, the teeth extremely 
minute. But the most characteristic parts of the creature 
are the scales. They are of great size, compared with the 
size of the animal. An individual not more than half a foot 
in length, the specimen figured, (see Plate V., fig. 2,) exhib 
its scales fully three eighth parts of an inch in diameter. In an- 
other more broken specimen there are scales a full inch across, 
and yet the length of the ichthyolite to which they belonged 
seems not to have much exceeded a foot anda half. Each scale 
consists of a double plate, an inner and an outer. The struc- 
ture of the inner is not peculiar to the family or the forma- 
tion: it is formed of a number of minute concentric circles, 
crossed by still minuter radiating lines — the one described, 
and the other proceeding from a common centre. (See Plate 
V., fig. 5.) All scales that receive their accessions of 
growth equally at their edges exhibit, internally, a correspond- 
ing character. The outer plate presents an appearance less 
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