THE LOWER DEVONIAN FISHES OF GEMUNDEN,—SUPPLEMENT. 475 
EXPLANATION OF THE PLATES. 
All the figures in the following plates have been reproduced from photographs taken from specimens from 
the Lower Devonian Roofing Slate of Gemiinden in the Royal Scottish Museum. 
m.d., median dorsal plate. p.l., postero-lateral. 
m.v., median ventral. f.p.l., right postero-lateral. 
m., mental. L.p.l., left postero-lateral. 
Z., SENSOTY. d.f., dorsal fuleral scales of tail. 
a.v.l., anterior ventro-lateral. v.f., ventral fulcral scales of tail. 
p.v.l., posterior ventro-lateral. ¢., position of cloacal opening. 
PuaTE I. 
Ventral surface of a carapace of Drepanaspis Gemiindenensis, somewhat deficient in front and on the left 
side. The specimen is strongly obliquely deformed, so that the lateral plates on the right side are shoved in 
advance of those on the left. Here we have an exceedingly good view of the median ventral plate (m.v.) 
with its posterior median fold and notch, and the anterior emargination in which the hinder portion of the 
mental plate (m.) is seen to be lodged. Owing to oblique displacement of parts, the hinder portion of the 
internal surface of the median dorsal plate (m.d.) is also seen below and behind the median ventral. 
Compare this figure with that on Plate III. of my previous memoir. 
Puate II. 
Fig. 1. Tail and caudal fin of Drepanaspis, to show the oblique heterocercal configuration, and the 
greater size and strength of the fulcra on the upper or dorsal margin. The lateral scales of the tail-pedicle 
in front of the caudal fin are covered with pyritous deposit, and the commencement of the row of dorsal 
fulera is also not exhibited. Natural size. 
Fig. 2. Specimen of Drepanaspis somewhat deficient on the left side, lying on its ventral surface, but 
with the median dorsal plate wanting, so that the zmmer surface of the median ventral is exposed. At the 
antero-external corner of the carapace the small rounded pit formed by the compression of one of the external 
dorsal polygonal plates over the internal ring-like thickening of the opening in the sensory plate is well 
marked ; behind this, the outer margin of the carapace and its postero-lateral angle are formed by the 
postero-lateral plate. The median row of dorsal fulcra is seen from its commencement, and the two rows of 
vertically elongated scales on the side of the tail-pedicle are unusually well shown. The ventral fulcra are 
not seen, having been cut off by the broken edge of the stone, but a great part of the expanse of the caudal 
fin, covered with small rhombic scales, is visible, One-half natural size. j 
Puate III. 
Specimen of Drepanaspis Gemundenensis lying on its back, and showing the greater part of the outer 
surface of the median ventral plate (m.v.) with the posterior mediag fold, and the notch c. marking the 
position of the cloacal opening. ‘This notch is followed by the line of rfedian ventral fulcral scales (v.7.), the 
first of which is slightly displaced in front, so that its anterior margin no longer completes, as it ought, the 
notch into an opening. ‘The dorsal fulcra (d,f.), of obviously larger size, are seen on the opposite side of the 
tail, the anterior ones being slightly confused. The scales of the beginning of the tail-pedicle are, as is 
commonly the case, obscured by pyritous deposit, but those further back and on the caudal fin are clearly 
exhibited. Portions of the left sensory plate (x.), of the left anterior ventro-lateral (a.v.l.), and of the left 
postero-lateral (L.p./.) are seen at the top of the figure ; a portion of the right postero-lateral (A.p.l.) is also 
seen below, removed from the rest of the fish, and turned right over so as to show its dorsal surface. Lastly, 
the median dorsal plate (m.d.) is so displaced from the rest of the body as to be seen almost in its entirety, 
—seen, of course, from its internal or visceral aspect. 
