422 CLASSIFICATION OF DEVONIAN FISHES 
the only known species of its genus, isa fish with an elongated body, a 
depressed head and a conically tapering caudal extremity. The orbits 
are situated forwards, while the gape extends far back. The frontal 
S K, 
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NIN WON Ca los 
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CG OAL 
ae 
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Fig. 1. Restoration of G.yptolemus. 
bones (fig. 2) are distinct from one another and from the parietals, which 
last are not shorter than the frontals, and, though in contact through- 
out the whole length of their inner margins, are perfectly distinct from 
one another. Three bones, or scales (for they seem to partake as 
much of the nature of the latter as of the former), a median and 
two lateral, roof in the occipital region. The middle of the jugular 
Fig. 2. Diagram of the Head of Glyptodemus.—For an explanation of the letters, 
see p. 460. 
region, or that comprised between the two rami of the mandible 
upon the under surface of the cranium, is occupied by two large, 
triangular, squamiform, bones—the principal jugular plates (J); 
