206 
ERIK A : SON STENSIO 
The cranial section of the main lateral line of the body has, as usual, constituted 
the direct posterior continuation of the infraorbital canal. 
Nothing is preserved of the other sensory canals. 
Axial skeleton. 
As the scales are rather small and thin it is evident that the ossifications of the 
axial skeleton are more easily accessible for investigation than in the majority of 
Palaeoniscids. Remains of the axial skeleton are found preserved in P. in and P. 6jic. 
The chorda seemed apparently well developed, as in Palaeoniscids in general. 
The basidorsals ( Bd , PL 26, fig. 2) are represented in the abdominal region by 
comparatively short and robust bones. In the anterior part of the caudal region basidorsals 
are also found preserved, but it is obvious, however, that they increase in height 
towards this region, their distal part becoming narrow at the same time. 
Interdorsals cannot be shown with complete certain¬ 
ty, but one may undoubtedly conclude that they were 
small and mainly cartilaginous. It is noteworthy that they 
perhaps extended in a basal direction so that they covered 
a dorsal part of the chorda on the lateral sides. This 
seems to be the case, at least to judge from certain frag¬ 
ments of bone on P. 6yi c. 
The unpaired neural spines (Nsp, PI. 26, fig. 2) consist 
as usual of a row of free ossified, elements, correspond¬ 
ing in number to the basidorsals. Similar neural spines 
are developed in the whole abdominal region and at 
least in the anterior part of the caudal region, where, 
however, they begin tn decrease in length and to be 
replaced by the lengthened basidorsals themselves. 
It is very noteworthy that these unpaired neural 
spines are not situated so as to form a direct continua¬ 
tion of the basidorsals in a distal direction but so that 
they really come into contact with the anterior margin of these. Each of the unpaired 
neural spines thus corresponds most closely to the gap between two successive 
girdle. After P. in. V 2 . 
Cl, cleithral; Jcl, clavicle; Md, mandibula; 
Mx, maxillary; Op, operculum; Po, pre¬ 
operculum; Rbr, branchiostegal ray; Scl, 
sup'racleithral; Sop, suboperculum; Sscap, 
suprascapular. 
basidorsals. 
The unpaired neural spines seem generally to have had a similar position also in 
other Palaeoniscids (cf. Coccolepis, Woodward 1895 a, PI. 1, fig. 1; Phanerosteon Traquair, 
1911a, p. 166, text fig. 9; etc.), higher ganoids ( Caturus , Hypsocormus, Woodward 1898 a, 
text figs. 76, 78; Amia, Goodrich 1909, text fig. 3 iiB) and many primitive Teleosts 
( Leptolepis , etc. Woodward 1898 a, text fig. 80 etc.). In a number of other Teleosts they 
are also shown to exist, though there they are rudimentary (Schauinsland 1905, p. 468, 
text fig. 261). According to Zittel’s figure of Dorypterus (Zittel, 1887—1890, text fig. 264) 
they also occur in Platysomids. 
What has already been put forward strongly supports the view that the unpaired 
neural spines are not to be considered as distal segments of the basidorsals. They may 
instead of that represent a distal part of the interdorsals, a view that has been maintained 
