TRIASSIC FISHES FROM SPITZ BERGEN 
57 
also deepened into a groove in the longitudinal direction of the skull. The two lateral 
surfaces are high and narrow and are hidden in their lower part by the anterior ends 
of the prootico-opisthotics, as has already been pointed out. 
At the anterior corner of the upper surface, on the right and left sides of the 
corpus, there issues in a forward, upward and somewhat lateral direction a powerful 
process e (text figs. 19, 20, 22; PI. 4, figs. 1, 2; PI. 5, fig. 1; PI. 6, figs. 3 , 4; PI. 7, fig. 5; 
PI. 8, fig. 1) which increases in width and thickness distally and is rather abruptly 
truncated at its end. The ventral processes (v, text figs. 19, 20, 22) are sent out from 
the corpus near its ventral corner. They exhibit a slight divergence in the ventral 
direction and like the dorsal ones they also increase both in width and thickness distally. 
Their ventral ends rest on the parasphenoid bone, and since, as has already been pointed 
out, the corpus does not reach so far down, there arises between them a rather high 
but fairly short square longitudinal canal (m, text figs. 20, 22), which 
is bounded dorsally by the corpus of the basisphenoid and ventrally 
by the parasphenoid. The anterior surface of the ventral processes 
is smooth, like the lateral one, which is bounded from the former by 
a sharp vertical edge. 
The anterior face of the corpus of the basisphenoid is free 
only in its median part. Its right and left borders form a fastening 
for a lamella which points forward and at the same time some¬ 
what laterally ( al , text figs. 19, 20, 22; PI. 4, fig. 1; PI. 5, fig. 1, PI. 8, 
fig. 1). From the lateral sides and partly ventrally as well the two 
lamellae together bound a large fossa that is open at the front 
and upwards (text figs. 20, 22). The lamellae are rather thick at 
their postero-dorsal parts and form there a support for the proximal 
end of the process e on its ventral side. Their antero-dorsal parts 
are situated against the antero-medial border of the same process 
and attain the same height as the dorsal surface of the latter. Seen 
from above, they themselves are consequently visible on each side 
as a long narrow process, situated close to the antero-medial border 
of the process e (text fig. 20). The ventro-caudal process, from the dermal cranial roof, which 
corresponds to the alisphenoid (. Alspli , text fig. 20; PI. 4, fig. 1; PI. 5, fig. 1; PI. 8, fig. 1) 
joins their upper anterior corner on each side. Anterior to and at a level just below the 
process e on the lateral surface of the lamellae in question, where these are thickest, there 
is a little cavity in which a rather fine canal opens {Vj e _ text figs. 19, 22). The inner opening of 
this canal ( V llt text fig. 22) is found on the medial side of each lamella in its postero-dorsal part. 
From the description and the figures given it is thus shown beyond all doubt that the 
basisphenoid is an unpaired bone, which cannot in any way be considered to enclose or sur¬ 
round the labyrinth. On the contrary it seems certain that the labyrinth stood in relation to 
the prootico-opisthotic and under these conditions it is most probable that its anterior part 
was situated in the backward and upward opening cavity in this bone. Behind the corpus of 
the prootico-opisthotic the capsula auditiva has been cartilaginous, probably to the extent 
shown by text fig. 21, and the posterior part of the labyrinth has apparently been 
situated in this cartilage. 
S ten si 6, Triassic Fishes from Spitsbergen. 8 
Rsph- - 
Text fig. 22. 
Wimania sinuosa n. sp. 
The basisphenoid in anterior 
aspect. From P. 25 j. »/ 4 . 
Bsph, basisphenoid; Psplt, 
parasphenoid (in cross-sec¬ 
tion); al. forward pointing 
lamella from the basisphe¬ 
noid corpus; c, basiptery- 
goid process; in, the anterior 
opening of the myodome: 
v, ventral process from the 
basisphenoid corpus; V, e 
outer opening of the canal 
for n. ophthalmicus pro¬ 
fundus; V,> inner opening 
of the canal for n. ophthal¬ 
micus profundus. 
