TRIASSIC FISHES FROM SPITZBERGEN 
91 
The primordial neurocranium and its ossifi¬ 
cations. 
The primordial neurocranium is on the whole 
wider and more powerfully built than in W. sinuosa 
and relatively to its length it is not inconsiderably 
higher than in this species (text figs. 3g, 40, 43, 44). 
The snout has probably been rather blunt and so 
resembles in profile to a certain extent that of the 
Palaeoniscids. 
Nothing is preserved of the occipital region. 
The labyrinth region is fairly long and at • 
the same time considerably wide. It seems to have 
consisted of cartilage to about the same extent as 
n W. sinuosa and presumably had, as in this species, 
a paired muscle groove (temporal fossa») on the 
posterior part of the dorsal surface. A number of, 
remains of the prootico-opisthotic (Pro. 0, Pis. 11, 
12, 13); indicate that this bone has been well de¬ 
veloped, but nothing more can be said as to its 
shape. A posterior smaller part of the basisphenoid 
also belongs to the labyrinth region. 
The orbitotemporal region is somewhat shorter 
and broader than in W. sinuosa. The breadth especi¬ 
ally is greater, if one pays attention to the ventral 
parts (text figs. 40, 41, 42; PI. 14, fig. 5; PI. 16, fig. 1). 
The basisphenoid is situated, as usual, in the pos¬ 
terior end of the region in question but is rather 
low and, contrary to the case in W. sinuosa, by no 
means reaches to the cranial roof dorsally. A 
considerable part of the lateral wall of the neuro¬ 
cranium above it has been cartilaginous. The ante¬ 
rior and by far the greater part of the orbito¬ 
temporal region, which forms the real interorbital 
wall, has probably been composed entirely of carti¬ 
lage. With regard to the supposed fenestration 
which is situated! immediately in front of the 
ventral part of the basisphenoid and which is 
supposed to correspond to the orbital opening of 
the myodome, according to what I have tried 
to show in W. sinuosa, nothing particular can 
Text fig. 40. Axelia robusta n. sp. 
Neurocranium from the dorsal side with the roof 
removed above the occipital region, the labyrinth 
region, and the posterior part of the orbitotemporal 
region. From P, ig 5 . »/,. (The prootico-opisthotic 
incompletely preserved in this specimen and there¬ 
fore not drawn.) 
Alsph, alisphenoid, joined to and forming a ventro- 
caudal process from the fronto-dermosphenotic; 
Bsph, basisphenoid; Fr. dsph, fronto-dermosphe¬ 
notic; Ir, interrostral; Na. ant, nasalo-antorbital; 
Psph, parasphenoid; Plr, postrostral; R, rostrals; 
So, supraorbitals; al, anterior lamella from the 
basisphenoid corpus; e, basipterygoid process; 
na lt anterior nasal aperture; na 2 , posterior nasal 
aperture; p, pores of the sensory canal; furrow 
on the lateral side of the alisphenoid, indicating 
the course of the n. ophthalmicus lateralis; s, ver¬ 
tical furrow leading down to the entrance of the 
supposed myodome; V 2 , 3 , sinus in the basisphe¬ 
noid corpus situated under or in relation to the 
foramen or foramina transmitting r. maxillaris 
trigemini, r. mandibularis trigemini, n. ophthal¬ 
micus trigemini and n. ophthalmicus lateralis. 
be added to what has already been said in the description of the latter species. 
The basisphenoid {Bsph, text figs. 3g, 40, 41; Pis. 11 — 13; PI. 14, figs. 2, 3, 5) consists 
partly of cancellous, and partly of radiate, bone substance. The latter sort, however, is 
12* 
