TRIASSIC FISHES FROM SPITZBERGEN 
III 
Geological occurrence and localities. — M. spinosus is only known from the 
fish horizon, where it occurs sparsely. Of the three specimens here referred to P. 2/5 is 
from Mt Andersson and the other two from Mt Congress. 
Genus Scleracanthus n. g. 
The genus for which I have chosen the name Scleracanthus is, like the preceding 
one, still very incompletely known. Its most typical characters may be summarized as 
follows: Large fishes. The neurocranium probably robustly built on the whole. Its 
sculpture is strong, consisting of long, sharp striae. The pterygoid is thick and robust, 
probably with a high posterior and a low anterior limb; the anterior limb with a deep 
sinus on the dorsal margin. The dentition is strong, adapted for crushing; the tooth¬ 
bearing parts of the medial surface of the anterior pterygoid limb are raised in relation 
to the toothless parts. The sensory canals are strongly developed and have large pores. 
The anterior dorsal fin is large, consisting of about 15 broad lepidotrichia, unjointed for 
a long way proximally; each of the lepidotrichia has two rows of sharp tubercles on 
the lateral surfaces. The scales are rather triangular in shape with a high, pretty straight 
or weakly convex anterior and a pointed posterior margin. The sculpture of the scales 
consists of strong, fairly long longitudinal striae, somewhat parallel or sometimes slightly 
converging posteriorly. 
As far as one can judge from the facts so far known, Scleracanthus seems in several 
respects to be related to Mylacanthus in the same way as the latter in its turn 
appeared to be closely allied to Axelia. But it is well distinguished from Mylacanthus 
by having a stronger pterygoid, stronger dentition, a very different shape of the scales 
and also a different sculpture. Of course it also offers certain clear resemblances to 
Axelia, but the differences from this genus are, however, rather marked. In this case 
the development of the fins is especially different. 
In addition it may be pointed out that the sculpture of the scales in Scleracanthus 
partly resembles that of certain Carboniferous Coelacanthus species (cf. Huxley, 1866, PI. II, 
figs. 3 , 4; PI. Ill, figs. 1 a, 3 a), as is also the case with the shape of the scales, though 
this has also certain similarities with the shape described above for Wimania? multistriata. 
Scleracanthus asper n. sp. 
(PI. 17, fig. 3; PI. 18, fig. 2; PI. 19, figs. I, 2; PL 20, fig. I.) 
S. asper is represented by a few incomplete specimens (P. 2Sg — 242, P. yog) with 
remains of the visceral skeleton, axial skeleton, fin skeleton and squamation. 
With regard to size this species certainly immediately followed W.? multistriata 
among the Spitzbergen species. But it is not possible to obtain any reliable measurements 
which can give us an exact idea of its proportions. 
Visceral skeleton. 
The pterygoid ( Pt , PI. 18, fig. 2), which is incompletely preserved, is very thick and 
strong, especially at the anterior limb. The posterior limb was apparently high, with a 
deep sinus in its dorsal margin. This sinus was, however, broader than in Mylacanthus 
