382 Proceedings of the Royal Physical Society. 
is a Selachian spine, which, in its general conformation, 
belongs to the Gyracanthus-type, however different may be 
the character of its surface ornament. 
Holoptychius decoratus (Eichwald). 
[Plate XI., Fig. 6.] 
Sclerolepis decorata, Eichw., Bull. Soc. Imp. Nat. Moscow, vol. xvii., 
1844, p. 832; Zbid., vol. xix., 1846, pl. x., figs. 16,17. Lethea 
Rossica, vol. i., 1860, pl. 57, fig. 7. Holoptychius decoratus, Traq., 
Ext. Verteb. Moray Firth Area, p. 254, pl. vi., fig. 11. 
Among the fossils from Scaat Craig in the Brickenden 
Collection (P. 8275) is an imperfect scale in a coarse reddish 
grit, which I cannot distinguish from the fossiliferous stone 
of that locality, and from which we must therefore presume 
that it was derived. 
This specimen is represented magnified two diameters in 
Pl. XI., Fig. 6; it is 1 inch in length, but it is only the 
exposed portion of the scale which is anything like entire. 
The covered area is broken away on one side in front; what 
remains of it is covered with a beautiful and minute granula- 
tion. The exposed part of the surface shows first a zone of 
the tubercles characteristic of H. decoratus, this zone being 
a quarter of an inch broad in the middle, but narrowing 
towards the sides. Behind this the tubercles are smaller, 
and tend to become elongated backwards as fine elevated 
antero-posterior ridges or striz, similar to those represented 
by Eichwald in his second figure given in the “ Lethea 
Rossica,” as quoted above. 
I have no doubt of the correct identification of this scale, 
and as it occurred among the Scaat Craig specimens in the 
Brickenden Collection, and on a matrix indistinguishable 
from the harder portions of rock in that locality, we must 
presume that we have here proof of the extension of the 
species in Scotland to another horizon than that of the 
Nairn Sandstone, in which it has hitherto only been 
found. 
