TRIASSIC FISHES FROM SPITZBERGEN 
9 3 
the proximal parts of these. While in W. sinuosa they reach anteriorly as high as the 
dorsal surface of these processes, here in A. robusta, on the other hand,' they only 
extend to the ventral one. 
The posterior part of the fossa hypophyseos, bounded by the basisphenoid corpus 
and the anterior lamellae, is strikingly broad (text figs. 40, 41; PL 14, figs. 3 , 5). From 
its base there passes vertically downwards to the supposed myodome ( m ) a median 
furrow ( s ) which has obviously formed the posterior part of an unpaired canal, whose 
anterior part has been surrounded by cartilage. This canal seems 
to have been in relation with the hypophysis. On the medial 
surface of the anterior lamellae we notice a rounded torus (r) 
running anteriorly and somewhat downwards and immediately 
above it a furrow, also running anteriorly and downwards, which 
becomes deeper as it continues anteriorly and leads into the 
canal for n. ophthalmicus profundus ( Vn , text fig. 41), which canal 
penetrates the dorsal part of the lamella in an outward and 
somewhat downward direction and has its external opening F, e , 
(text figs. 3 g, 41; PL 14, fig. 5) about ventro-medially of the 
anterior end of the basipterygoid process. 
The cranial cavity in this species seems in the main to 
have been similar to that of W. sinuosa , except that is was broader 
and higher. The exits of the nerves, at least in the orbito¬ 
temporal region, have also had a similar position in both species. 
The canal for n. ophthalmicus profundus has, as we have seen, 
about the same position as in W. sinuosa and the same is true of 
the other trigeminal branches and the r. ophthalmicus lateralis, 
all of which have their exits (V 3 , s , text figs. 3 g, 40) in A. robusta 
above the lateral margin of the dorsal surface of the basisphenoid 
corpus either in relation to this margin or a short distance 
dorsally of it, totally in cartilage. The n. ophthalmicus lateralis 
(and possibly n. ophthalmicus trigemini as well) has probably 
had its exit through a separate foramen somewhat dorsally of 
the other or else it has been transmitted through the dorsal part 
of the same foramen with these. After its exit it has in all prob¬ 
ability had its course anteriorly along the lateral wall of the neurocranium above the 
basipterygoid process and in this course it has crossed the ventro-caudal process (Alsph) 
of the fronto-dermosphenotic. Its course is indicated in the fossil by a well marked 
groove (r. ophth, text figs. 3 g, 40; Pl. 11, PL 14, figs. 2, 3 ). Other nerve formina in the 
cartilaginous parts are hypothetically drawn in text fig. 3 g in accordance with Dictyonosteus, 
as in the case of W. sinuosa. 
The ethmoidal region of the species in question is high and rather broad (text 
figs. 39, 44; Pis. 11—1 3 ; Pl. 14, figs. 1, 4) and has consisted mainly of cartilage. Only a 
paired bone ( Pethm , text figs. 3 g, 42; Pis. i2 ; 1 3 ; Pl. 16, fig. 1) is developed. The nasal 
capsule has probably been situated in the cartilage above the posterior and medial 
part of this bone, but, as will be seen, without having any direct relation to it so as to 
Text fig. 42. 
Axelia robusta n. sp. 
Parasphenoid and preethmoid in 
ventral aspect. The parasphenoid 
with teeth. From P. ig 5 . %. 
Pethm, preethmoid; Psph, para¬ 
sphenoid; f. pal, foramen for 
the dorsal branch of n. palatinus 
anterior; lat. for, foramen for 
the most anterior branches of 
n. buccalisand r. maxillaristrige- 
mini; ms, furrow along the lateral 
side ot the preethmoid for n. 
buccalis lateralis and r. m axillaris 
trigemini. 
