TRIASSIC FISHES FROM SPITZBERGEN 
85 
ween S. tuberculata and Undina gulo. In other words, with regard to the sculpture 
of the scales and also the cranial sculpture Sassenia resembles in certain respects 
at the same time both the Coelacanthus and the Undina-Macropoma type, and it 
seems also to occupy a similar intermediate position with regard to the shape of 
the posterior pterygoid limb. 
The resemblance between Sassenia tuberculata and the Undina species from the 
Cava Trefontane referred to is so great that one may even feel doubtful whether fte 
have not really two species of the same genus present here, i. e. that the supposed 
Undina species from the Cava Trefontane would really belong to Sassenia. As at least 
one Actinopterygian genus, Perleidus, seems to be common to the Triassic of both 
Spitzbergen and Lombardy, this may to a certain extent indicate that with a complete 
knowledge of the two faunae we may expect to find still more common forms. But the 
fact that, if we judge merely from the sculpture of the scales, we have pretty much 
the same right to group together Undina gulo in the same genus with S. tuberculata 
shows us how careful we must be in deciding a case of this sort. The question as to 
whether Sassenia also includes the species from the Cava Trefontane described as 
Undina sp. must therefore be left undecided. 
The name Sassenia for this genus is derived from the Sassen Valley. 
Sassenia tuberculata n. sp. 
(Pi. io), 
Sassenia tuberculata is represented only by three incompletely preserved specimens 
(P. 224 — P. 226) with portions of the head and the squamation. These three specimens all 
come from individuals of rather average size. The maximum height of the head — the 
only measurement at all reliable that can be obtained — may thus be probably estimated • 
at about 6—7-5 cm. 
The ossifications of the primordial neurocranium. 
Of the ossifications of the primordial neurocranium the prootico-opisthotic (Pro. o, text 
fig. 37) and the basisphenoid ( Bsph, text fig. 37) are only preserved fragmentarily. As 
far as can be seen, they have both been developed essentially as in W. sinuosa, but the 
nature of the material does not permit of any detailed comparison. 
The membrane bones of the neurocranium. 
Posteriorly beneath the labyrinth region the parasphenoid ( Psph, text fig. 37) has 
had the same slight extension as in W. sinuosa. In its anterior parts it is incomplete, 
but all the same it is obvious that it had lateral parts that were bent upwards and 
between these a somewhat thickened horizontal portion with teeth; just as in W. sinuosa, 
this thickened portion is not developed behind the centre of ossification. 
The membrane bones of the cranial roof are not known, except for the supratemporo- 
extrascapular ( Stemp. ext , text fig. 35; PL 10, fig. 1) and the parieto-intertemporal {Pa. it, 
text fig. 35, PI. 10, fig. 1). These two bones, though partly deformed by pressure and 
incomplete in other respects, seem to have been in the main similar to those in W. sinuosa. 
