68 
ERIK A : SON STENSIO 
much shorter than the posterior one. The anterior margin is characterised also by two 
narrow, deep sinus with an anteriorly projecting process lying between them. At the 
obtuse end of this process a sensory canal enters the squamoso-preopercular, where 
it continues in anarch backwards and downwards ( jc, PL 5, fig, 4) to the lower margin, 
which it reaches not far in front of the postero-ventral corner. 
The preoperculo-quadratojugal (Pop. quj, text fig. 25; PI. 5, figs. 2, 4; PL 6, figs. 1, 
2, 3 , 4; Pl. 7, fig. 5) is situated externally of the ventral part of the palatoquadrate. Its 
breadth is probably about twice as great as its height. Its shape, in respect to the 
lines of the contour, is not fully known with certainty. From the squamoso-preopercular 
a sensory canal has continued in a ventral direction and ought, according to what one 
can judge, to have also entered the preoperculo-quadratojugal in its posterior part. 
Concerning this bone it is further to be remarked that it is of a considerable thickness, 
and has a well discernible centre of ossification in the postero-ventral half. 
The lacrymo-jugal (La. ju, text fig. 25; Pl. 5, figs. 2, 4; Pl. 6, fig. 2) is a long and 
on the whole narrow bone arched in such a way that it has the concavity dorsally and 
the convexity ventrally. Is is highest (broadest) in its posterior part for about a third 
of its length. In front of this there follows a lower middle part, lying under the orbital 
opening, and yet again still more forward there is a somewhat higher but shorter part 
lying preorbitally, after which the remaining anterior part rather slowly decreases in 
height to the end, which becomes pointed. The posterior end, which is turned dorsally, 
is, on the contrary, blunt. In its posterior part the bone probably came into contact 
with, or in any case has lain very near to the process of the anterior margin of the 
squamoso-preopercular. Dorsally, on the other hand, it does not by a long way reach 
to the postorbital, but is connected with the latter, as far as one can understand, by a 
little four-sided plate (X, text fig. 25, Pl. 6, fig. 2), situated in a sinus open in front, 
which is bounded dorsally by the postorbital bone, caudally by the squamoso-preopercular, 
and ventrally partly by the latter and partly by the upper end of the lacrymo-jugal. 
The anterior end of the lacrymo-jugal has probably extended a good bit forward along 
the lateral surface of the ethmoidal region, as text fig. 25 shows. A part of a sensory 
canal pierces the plate X as well as the lacrymo-jugal. 
All the cheek plates are, as far one can see, quite without ornament of ganoine. 
The postorbital and the squamoso-preopercular show plainly concentric lines of growth, 
while the preoperculo-quadratojugal, on the contrary, as already mentioned, has a well 
developed radiate bone structure. 
The cheek plates of the species under consideration have not fitted with their 
margins towards each other so as to form a continuous covering of bone, but must have 
lain losely in the corium in about the same way as they are found in the fossil. Partly 
they are even separated from each other by considerable interspaces. A specially large 
interspace seems to have existed behind the postorbital plate, as the squamoso-preoper¬ 
cular does not reach so high upwards as in Coelacanthus (Wellburn, 1902, p. 475, fig. 
pag. 483) and no independent smaller plate seems to have existed here, which is the 
case in the species Sassenia tuberculata, described later on. Another large interspace 
seems to have been developed between the squamoso-preopercular, the preoperculo- 
quadratojugal, and the posterior part of the lacrymo-jugal bone. 
