ERIK A : SON STENSIO 
I 6 
longitudinal crista. But notwithstanding this it can scarcely be said that there is any real 
continuous secondary longitudinal crista developed on this part of the tooth, but it is not 
impossible that there has been one nearer the transversal crista, • i. e. towards the middle 
part of the tooth. On the medial side of the crown most of the striae reach continuously 
from the basal margin to the primary longitudinal crista. Towards the end of the tooth 
they run quite transversally, while more towards its middle part their distal ends are 
curved considerably towards the transversal crista. Under these conditions they conse¬ 
quently meet the primary longitudinal crista at an acute angle. In this way the middle 
part of the crown acquires a very characteristic feature, as all the striae converge, as 
it were, towards the point where the primary longitudinal and the transversal crista 
cross each other. The details of the sculpture are further shown in PI. 2, fig. 17 and 
will be treated more thoroughly below in a similar tooth which is better preserved 
(P. 98 j). On the medial side the crown projects rather considerably out over the root, 
with which it forms in this way a notch like that on the tooth P. 98 h. The basal surface 
of the root is oblique in the usual way, so that it faces ventero-laterally. 
In the material from the Triassic of Horn Sound there is a tooth which, as far 
as it is accessible for investigation, seems to resemble P. 98 1 . It is, however, consider¬ 
ably smaller. 
The tooth P. 100 (PL 2, fig. 18) is better preserved than the majority of those 
previously described and there is rather more than the one half of it present. The 
original length seems to have been about 24 mm. Its greatest height is about 8 mm. 
The crown has a rather distinct and comparatively long, though low, transversal 
crista, which is abundantly ramified both at the lateral and medial ends. Curiously 
enough, no angle is developed at the place where the transversal crista is situated, 
but the outline of the actual masticatory surface is well rounded in the longitudinal 
direction both in medial and in lateral aspect. A primary longitudinal crista is present 
and at the end part of it there is on both sides a short secondary crista as well. The 
striation is developed approximately equally on both sides of the primary one and the 
striae extend continuously from this to the basal margin of the crown. Their distal 
ends all curve towards the transversal crista and meet the primary longitudinal one at 
an acute angle, as was the case with certain of the striae on the above-described 
tooth P. 98 m. 
Seen from the medial side, both the root and the crown have been fairly straight. 
From the lateral side, on the other hand, the crown seems weakly bent. The crown 
projects out over the root on the medial side and forms a considerable notch. The 
basal surface is very oblique and forms an angle of about 45 0 with the prolongation 
of the axis of height of the crown. It faces ventro-laterally in the usual way. 
The tooth P. 98] (PI. 2, fig. 19) is the best preserved of all the teeth that I have 
included here among those of the middle and posterior transversal rows. Its length 
may be estimated at about 25 to 28 mm and its greatest height is about 9 mm. Both 
the root and the crown are bent in the vertical plane through their axis of length in 
the same way as has already been described in a number of teeth and the curvature 
is strikingly strong in the case of the crown. The crown is somewhat higher and 
broader in the middle than towards the ends. As it is somewhat injured in the middle 
