56 
ERIK A : SON STENSIO 
between the processes of the two sides. As we know, the basioccipital both in fishes 
and in other vertebrates extends as a rule a considerable distance forward in the basis 
cranii, and the fact mentioned need not therefore indicate in any way that the lateral 
occipital, as Huxley thought, includes the bone interpreted by me as the prootico- 
opisthotic. In addition it seems also probable that the basioccipital in Undina represents 
only the most anterior part of the bone that in the Teleostomes we call under ordinary 
circumstances the basioccipital. 
The bone in the Coelacanthids that was taken by previous authors (Huxley, 1866, 
p. 35; Reis, 1888, pp. 25, 62— 63 ; 1892, p. 21; Heineke, 1907, p. 12) to be the prootic is 
unpaired and, as I have said in a previous work (Stensio. 1918 c, p. 120), corresponds 
to a basisphenoid. In Dictyonosteus its homologue forms an integral part of the large 
unpaired bone which extends there through the whole orbitotemporal region and which 
now, in accordance with the conditions in Polypterus, I consider ought to be termed a 
sphenoid (Traquair, 1871). Besides the basisphenoid there is also in the Coelacanthids a 
paired bone homologons, to the dorso-caudal part of the sphenoid of Dictyonosteus and 
this bone in Coelacanthids is apparently most closely comparable with an alisphenoid al¬ 
though, as we shall see, it is coalesced secondarily with a bone in the dermal cranial roof. 
By far the greater part of the basisphenoid in W; sinuosa is situated (Bsph, text 
figs. 19, 20; PI. 4, figs. 1 — 2; PI. 5, fig. 1; PI. 6, figs. 3 , 4; PI. 7, fig. 5; PI. 8, fig. 1) in the 
caudal part of the orbitotemporal region, but at the same time it reaches a short 
distance into the most anterior part of the labyrinth region, as we shall see from the 
nerve exits and the configuration of the cranial cavity. The anterior end of the prootico- 
opisthotic reaches a short distance forward along the lower part of its lateral surface 
on each side and in this way forms a decidedly projecting part (f), which was described 
by Huxley, 1866, in Macropoma, although in his opinion it belonged to the prootic, 1 ') 
i. e. the bone termed by me the basisphenoid. 
The basisphenoid in Wimania sinuosa is, seen from the side (Bsph,' text fig. 19), 
rather short and high. It rests ventrally against the parasphenoid (Psph); dorsally it 
reaches up to and probably even partly comes into contact with the membrane bones of 
the cranial roof. Seen from above (text fig. 20) it appears short and wide. On it can 
be distinguished a corpus, and lamellae and processes issuing from the corpus. 
The corpus is composed of a cancelleous, the processes of a distinctly radiate, 
bony substance. The latter substance continues from all the processes into the corpus 
to a centre situated in the dorsal part of the latter. In shape the corpus is most compar¬ 
able to a triangular plate, fairly thick at the top, thinner below. Its bluntly rounded 
point is directed ventrally, but does not reach down to the parasphenoid bone (text 
fig. 22). Otherwise it is placed in such a position that it slopes backwards (text fig. 19). 
The large posterior surface consequently faces downwards to some extent, the anterior 
surface, which is narrower and hollowed out into a dorsi-ventrally directed g-roove, in 
the same degree upwards. The upper surface (fig. 20) is situated strikingly high, at 
about the same level as the upper part of the process fi on the prootico-opisthotic, 
and has about the shape of a rectangle with the margins somewhat concave. It _is 
*) The same opinion was still held by Reis in 1892. 
