150 
ERIK A : SON STENSIO 
representatives of a new genus, Boreosomus. The species noticed by myself in 1918 
(1918b, p. 77) as Gyrolepis? sp. also undoubtedly seems to pertain to the new genus for 
which I have suggested the name Glaucolepis. 
The Triassic of Spitzbergen has thus at least two genera of Palaeoniscids, Birgeria 
and Pygopterus, in common with the continental European Triassic formations (cf. 
Stolley, 1920, pp. 75— 83 ). 
Genus Birgeria Stensio. 
Synonym: Saurichthys (in part) Agassiz, Poissons fossiles, 1844, Vol. II, part II, p. 85. 
As I have had occasion to mention in an earlier notice (Stensio, 1919, pp. 177—178) 
we find in the Triassic of Spitzbergen remains of a large fish, which is apparently 
identical with or at any rate very closely related to Agassiz’s Saurichthys mougeoti 
(Woodward, 1895 b, pp. 20—21). A closer study of these remains clearly showed, as I 
had also mentioned, that the so-called S. mougeoti is distinguished from the typical 
Saurichthys species, and that it is impossible to refer it to the same genus as these, but 
it must be set up as the type of a new genus, for which I have suggested the name 
Birgeria after Dr. Birger Sjostrom my friend and companion during the Spitzbergen 
expedition of 1915. It has appeared, in addition, as is also pointed out in my notice, 
that the relationship between Birgeria and Saurichthys cannot be particularly close, and 
that the former apparently cannot be referred to the Saurichthyids, but must belong 
to the Palaeoniscids. 
The Rhaetic species S. acuminatus Agassiz (cf. Woodward 1895 b, pp. 21—22) ought 
also to be incorporated provisionally with the genus Birgeria, and with much hesitation 
I include in it another species, the so-called Saurichthys annulatus Winkler (Winkler, 
1880, pp. i 32 —135). For the reasons for this I refer to my critical revision of the genus 
Saurichthys below in this work (Part 2). 
Agassiz’s description of B. mougeoti was published in 1844 (vol. II, part 2, pp. 85—86). 
Already in 1837, however, the species in question was mentioned by Hogard (p. 405). 
Afterwards a large number of investigators, e. g. Giebel (1848, p. 257), V. Meyer (1849 a, 
p. 2o3; 1849b, p. 235), Quenstedt (1852, p. 23 i), Schmid (1861, pp. 21—22, erraneously called 
S. apicalis), Eck (1865, p. 120), Martin (1873, pp. 723—735), Reis (1891, pp. 153—154) 
and Woodward (1895 b, p. 20) have given more or less detailed descriptions of it. All 
the authors mentioned have, however, only been able to extend our knowledge of it very 
slightly, because of the very incomplete nature of the material available for them. 
The most important characters distinguishing the genus Birgeria can be summarized 
as follows: Large fishes. The head low and broad. Ossifications in the primordial 
neurocranium and the visceral skeleton strongly developed. Myodome in a primitive 
stage of development. Mouth large; suspensorium oblique. Maxilla of the usual 
Palaeoniscid-type with a sculpture of tooth-like tubercles. Dentition well developed; teeth 
pointed and conical with a vertically striated, two-edged enamel cap; basally of this 
sometimes only a vertical very fine striation; sometimes in addition rather coarse vertical 
ridges, which then in their turn have the fine striae; no plici-dentine is developed. Along 
the lateral margin of the maxillary and the dental there is a row of rather small teeth; 
medially of them is found another row of much higher and stronger teeth. The pterygoid and 
