430 CLASSIFICATION OF DEVONIAN FISHES 
another; in their form and relative proportions, these bones very 
much resemble those of Holoptychius. There are three bones in the 
superior occipital region, one median and two lateral. A_ trian- 
gular, single or divided, squamosal fits in between the parietal, the 
external of the three superior occipital bones, and some indistinctly 
defined supratemporal and postorbital plates; again, as in Holo- 
ptychius. (In the opercular apparatus, the operculum and _ sub- 
operculum are large, subquadrate, and nearly equal in size. There 
are large dendrodont teeth (very well shown in a large specimen in 
Sir P. Egerton’s collection) upon the inner side of the mandible. 
The principal jugular plates are large, but no specimen I have seen 
gives clear evidence of others. There is a well marked lateral line. 
Apart from what has been done by Agassiz, Miller, and Pander, 
5) 
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NX 
yA NO Wy us z 
: ee 
Fig. 7. Restoration of GlyAtolepis. 
I think I can venture to assert from my own investigations that 
the woodcut fig. 7 gives an essentially faithful restoration .of Glypto- 
lepis+ But a comparison of this figure with that of Holoptychius, 
given above, is sufficient to prove the close affinity of the two 
genera,—in fact, their family relationship. 
Pausing now, to look back over the ground which has been 
traversed, we find that the six genera which have been discussed 
viz, Glyptolemus, Glyptopomus, Gyroptychius, Holoptychius, Platyg- 
nathus and Glyptolepis possess the following characters in 
common :—Twwo dorsals, acutely lobate paired fins (ventrals of 
Glyptolepis); principal and lateral jugular plates, and no bran- 
chiostegal rays ; more or fewer large teeth with grooved bases, and 
consequently folded dentine ; sculptured scales and cranial bones,— 
among which last are to be noted three occipital plates,—large, 
1 Jt may be that the ventral fins are lobate, but I have seen no specimen justifying that 
conclusion. 
