TRIASSIC FISHES FROM SPITZBERGEN 
105 
the supraangulo-angular comprises, besides possible infradental components, both the 
homologues of the angular and the supraangular of the Rhipidistia. 
The homologues of the cheek-bones have already been dealt with in connection 
with the description of W. sinuosa. 
The axial and fin skeleton. 
The neural and haemal arches with their spines are, as usual, only ossified perichon- 
drally. Otherwise the spines are narrow and fairly long. Only in the caudal region at the 
transition between the proximal and distal segments are they somewhat thickened in the 
same way as in Wimania? sp. described above. 
The caudal fin has apparently been large (PI. 16, fig. 3 ), but apart from this 
nothing is known in detail about its shape or whether a supplementary fin had been 
developed. The number of its lepidotrichia seems to have been about twenty both dorsally 
and ventrally and all were long, narrow, and not expanded distally. On their lateral 
surface the lepidotrichia are furnished with a distinct longitudinal furrow, and both 
anterior and posterior to this furrow there are to be found small tubercles. At least 
on one lobe of the fin — it cannot be decided whether it is the dorsal or ventral one 
— the ten to twelve anterior lepidotrichia are undivided in their proximal parts for a 
long distance, while the posterior eight to ten show a few long joints at the corresponding 
parts. 
Some of the proximal ends of the lepidotrichia of the anterior dorsal 
fin are preserved in connection with a supporting bone-plate, which seems to have 
had about the same shape as in Coelacanthns granulatus (cf. Willemoes-Suhm, 1869, 
PI. 11, fig. 1). 
The shoulder girdle is badly preserved. It is true that remains of the cleithral and 
the clavicle can be distinguished, but little can be said as to their shape and their 
relations in general. 
The pectoral fin consisted of several fine, long lepidotrichia, which were jointed 
and branched dichotomically only in their distal parts. The joints seem in most cases 
to be fairly short. 
Squamation. 
In A. robusta the scales are comparatively large and are oval in shape with a rounded 
posterior margin. The exposed surface certainly varies fairly considerably in size in 
scales from different regions, but all the same it may be considered, on the whole, to 
be rather small. 
The sculpture (PL 16, figs. 3 , 5) consists of a number of fairly coarse striae, running 
horizontally; some of these are long and even stretch right across the exposed surface, 
others, again, are short, not infrequently almost tubercle-shaped. Sometimes some of the 
middle striae are thicker than the others situated dorsally and ventrally of them, and 
very often all or a number of these middle striae, too, are coarser and higher posteriorly 
than anteriorly. As far as one can see, the sculpture of the scales also varies somewhat 
according to their position. Thus it seems to be coarse on the middle and upper part 
of the sides of the body, while ventrally it is finer and weaker. 
* * 
Stensio, Triassic Fishes from Spitzbergen. 
