TRIASSIC FISHES FROM SPITZBERGEN 
265 
Dapedius), two very much enlarged sclales (Pci, PL 33 ; PI. 34, figs. 1, 2), the upper one 
of which is about twice as high as the lower one. 
The membrane bones of the shoulder girdle have the same sort of sculpture as 
the external ones of the head. 
The pectoral fins (Pc, PL 33 ; Pl. 34, figs, x, 2; Pl. 35, fig. 1) are relatively more 
strongly developed than the other fins. They are incompletely preserved and their shape 
cannot therefore be established with certainty. Their lepidotrichia number about 12 
—14 and have a rather long proximal part unjointed. Otherwise they are closely jointed 
and dichotomically ramified. The most anterior of them has numerous p 
but not specially strong fulcra. 
The ventral fins (V, Pl. 33 ; Pl. 34, fig. 1; PL 35, figs. 1, 3 ), 
which are situated considerably nearer the anal fin than the pectoral 
fins,'are strikingly short-based and consist only of 8 — 9 comparatively 
long lepidotrichia, which are jointed and dichotomically ramified only 
in their distal halves: Fulcra are clearly discernible. 
a 
Text fig. 84. 
Perleidus woodwardi. 
Scales from different 
parts of the body. After 
P. 1 S3. Vi- 
A) From the anterior 
part of the lateral sur¬ 
faces of the abdominal 
region. 
B) From the anterior part 
of the lateral surfaces of 
the caudal region. 
C) From theventral side. 
D) From the posterior 
part of the lateral sur- 
■ faces of the caudal 
region. 
S qp.amat.ion. 
The scales are thick and strong and because of this they are 
well preserved. Altogether one can probably count about 40 vertical 
rows of scales on a level with the main lateral line. In the rows 
immediately behind the shoulder girdle there are on the lateral sur¬ 
faces of the body as shown in Pl. 34, figs. 1,2 a number of scales 
that are higher than wide. Except for the scales on the ventral side, 
which are wider than high, the other scales have a rhombic or almost 
rhombic shape. The transition between the higher scales and the 
others takes place gradually. As Woodward (1912, p. 296) states, the dorsal ridge 
scales are certainly somewhat rhombic in shape, but at the same time they have a 
posterior margin developed which is finely serrated. While the height of the highest 
anterior lateral scales is about twice as great as the width or sometimes even more, the 
relation in the scales of the ventral side is quite the opposite, the width often being 
more than double the height. 
The anterior covered area of the scales is rather narrow but distinctly somewhat wider 
on the anterior scales than on the posterior ones (text fig. 84, A, B, C, D,). The dorsal 
margin has a well developed articulatory spine and the medial surface has a corresponding 
articulatory fossa at its lower margin. The antero-dorsal corner is also often somerwhat 
produced in the shape of a spine, as is clearly shown in text fig. 84 A, B and C. The ridge 
of the medial surface is weakly developed or is absent. The antero-ventral corner is 
always somewhat rounded, the postero-ventral one acute-angled, and the postero-dorsal 
one obtuse-angled. The posterior margin is serrated on all the scales, though not entirely, 
its dorsal part being always to some extent entire (text fig, 84). The small backward 
and downward directed serrations on this margin occur in great numbers only on the 
high anterior scales* (text fig. 84 A). Both on the scales situated upwards towards 
the dorsum, backwards and downwards they become less in number. Towards the 
posterior end of the caudal region there are scales of the type figured in text fig. 84 D. 
S tensio, Triassic Fishes from Spitzbergen. 34 
