TRIASSIC FISHES FROM SPITZBERGEN 
209 
On the most anterior scales the anterior covered area is comparatively wide. Its 
conditions on the scales following- farther posteriorly are not known with certainty, but 
it is most probable that it was not so wide as on the anterior ones. A strong and 
rather broad articulatory spine is developed on the dorsal margin of most of the scales. 
It is impossible to discover whether the antero-dorsal corner was also produced uppwards 
to form a sort of accessory articulatory spine as in P. humboldti. The vertical ridge on 
the medial side has either been absent or weakly developed. It was impossible to decide 
whether the posterior margin was serrated. 
The sculpture on all the scales consists of striation and, apart from the enlarged 
scales behind the cleithral, is rather fine. The striae in their turn are generally somewhat 
coarser at the anterior than the posterior ends, and are often ramified or somewhat situated. 
Some of them are long and extend over the whole exposed surface of the scales; others, 
on the contrary, are short and are wedged in here and there among the longer ones. 
On the anterior higher scales the striae are rather numerous and are all arranged 
so that they run more or less obliquely from the anterior and upper margins to the 
posterior and lower ones. Farther posteriorly this oblique striation is. restricted to the 
antero-ventral half of the scales, while the dorso-caudal half is gradually occupied by 
striae arranged parallel to the ventral and dorsal margins. The latter striae, of which, 
the ventral ones are, of course, the shortest, meet with their posterior ends the striae 
of the ventral half to form acute angles. The character of the sculpture on the scales 
close behind the shoulder girdle is shown by PI. 27, fig. 1. 
Remarks. — As has already been mentioned, Woodward (1912) hesitatingly gave 
the above described species under the name of Myriolepis? sp. That there can be no 
question of a Myriolepis species is, however, obvious, especially from the shape and 
development of the fins (cf. Traquair 1893, pp. 54—56; 1911a, pp. 162—164; Woodward 
1891b, p.515; 1906b, pp. 416—4x9; 1908a, pp. 14—17; Bolton 1894, pp. 1—4). It is also 
certain that the Spitzbergen species in question cannot belong to the genus Oxygnathus x ) 
either, and it seems improbable that it should be closely connected with Urolepis (de 
Allessandri 1910, pp. 42—49) or Platysiagum Woodward (1895 b, p. 533). 
On the other hand, it is not difficult to see that we are able to verify in it certain 
obvious points of agreement with Pygopterus, in the development both of the fins and 
the scales and the cranial skeleton, and consequently I have considered that I ought 
to refer it to this genus. 
Pygopterus de geeri is, on account of the sculpture, of the head, the shoulder girdle 
and the scales, and the shape of the anal fin, a well characterized species, which I have 
named after Professor G. de Geer of Stockholm, whose works have contributed so 
much to our knowledge of the geology and geography of Spitzbergen, and to whom I 
am much indepted for many valuable informations ..about Spitzbergen. 
Geological occurence and localities. — P. de geeri is only known from the 
fish horizon, where it occurs rather sparsely. 
I ) The species from the upper Karoo formation described by Broom (1909 a, pp. 259—262; PI. XIII, fig. 8) 
as Oxygnathus brownii really belongs probably not to the genus Oxygnathus but would seem to represent a new genus. 
Stensio, Triassic Fishe„s from Spitzbergen. 27 
