TRIASSIC FISHES FROM SPITZBERGEN 
107 
Skeleton of the fins. 
The caudal fin has probably been similar to that of the preceding species. The 
anterior dorsal fin (D ly PI. 17, fig. 1) has a short base and was very high in relation 
to the size of the fish. Several of its lepidotrichia are in their present condition not less 
than 9 cm in length and seem when complete to have been considerably longer (text 
fig. 49). Their exact number cannot be established with certainty, but in the present 
condition of the fin they amount to nine or ten. They are all slender and not expanded 
distally. At least in the distal parts their lateral sides had a weak tuberculation. The 
proximal parts are unjointed for a fairly long distance. The joints are short and almost 
square. The pectoral fins were probably rather weakly developed. Their lepidotrichia 
are all fine, and are jointed in about the distal two thirds (Pc, PI. 17, fig. 2). 
Squamation. 
The sculpture of the scales bears a fairly considerable resemblance to that of 
A. robusta (PL 16, fig. 7) but there are fewer striae, their number generally not exceeding 
eight and fairly often being only four or five. As a rule the striae 
are not so long that they reach across the free surface, but, on the 
other hand, short and more tubercle-like striae are also infrequent. 
Another difference from A. robusta is that the striae often show a 
slight divergence posteriorly. 
Remarks. — A. elegans is undoubtedly closely related to 
A. robusta but is also clearly distinguished from this species by 
the sculpture on the cranial roof and the opercular. Other minor 
differences can also be observed between the two species, e. g. in 
the extent and shape of certain elements in the cranial roof and the 
opercular apparatus. 
Geological occurrence and locality. — A. elegans occurs 
sparsely in the fish horizon. All the specimens come from Mt Congress. 
Text fig. 49. 
Axelia elegans n. sp. 
Lepidotrich from the 
anterior dorsal fin. From 
P. 223. %. 
Note the height in 
relation to the head in 
text fig. 48. 
Genus Mylacanthus n. g. 
The genus Mylacanthus is very incompletely known with regard to the skeleton 
of both the head and the body. Its most important peculiarities, so far known, are as 
follows: Rather large fishes. The skeleton of the head robustly built. Sculpture of the 
head consisting of somewhat elongated strong tubercles or short striae, arranged longi¬ 
tudinally and fairly parallel to each other. The posterior pterygoid limb is high and 
rather narrow; its upper margin has a deep angular sinus; the anterior limb, on the 
other hand, is comparatively low. The jmetapterygoid and the quadrate are high; the 
latter also particularly strong. The angular is high and triangular. The opercular large 
with a spiny or lobed postero-ventral margin. The dentition is strong and adapted for 
crushing. The sensory canals are much developed, with large pores. The scales are 
oval, with a sculpture consisting of short striae, diverging somewhat posteriorly. 
