20 
ERIK A : SON STENSIO 
Acrodus scaber n. sp. 
(PI. i, fig. 20.) 
Under this species name I have distinguished a number of fragments of teeth 
collected by Professor Dr. W. Salomon of Heidelberg from the bone-bed discovered 
during the excursion of the Geological Congress to Spitzbergen in 1910 (Stolley, 1911, 
p. 115). All the fragments belong to the collector. 
In two cases the fragments consist of fairly complete crowns. Otherwise there 
are mostly parts of crowns. Parts of roots are only preserved in two cases. 
All the remains so far present are 'from small teeth. The height of the crown 
seems in most cases to be not much more than 1 mm. In the two cases where the 
length can be established with any certainty it amounts to 2 and 3-5 mm respectively, 
but it has often certainly been somewhat greater. 
The 2 mm long crown (text fig-. 6) seems to have belonged to a tooth that was 
situated rather far forward, though not in the formost transversal 
rows. It is somewhat bent in the vertical plane through the axis 
of length in the same way as several of the teeth in A. spitzbergensis 
described above (text fig. 6), i. e. it is arched so that its basal 
contour is concave from one end to the other and its distal contour 
is correspondingly convex in the same direction. The highest part 
of the crown is situated about half way between the two ends 
and is not rounded but angular. A longitudinal crista is present. The rest of the 
sculpture, which is available for investigation only from one side, consists of a few 
strikingly coarse striae running from the basal margin of the crown to the longitudinal 
crista. Their course is, how r ever, not entirely transversal but is oblique in such a way 
that their distal ends are nearer the highest part of the crown than their basal ends. 
Some of the striae that are situated closest to the highest part do not reach directly 
from the basal margin to the longitudinal crista like those situated towards the ends 
but fuse more or less in the way shown by text fig. 6 with their distal ends to a 
secondary longitudinal crista. 
The 3 ; 5 mm long crown is developed with a longitudinal crista and the striation 
is of essentially the same type as was described on the preceding tooth. The striae 
are, however, more sparse and feeble. 
Three or four fragments of teeth resemble rather closely, as far as can be judged, 
the tooth P. 98 f of A. spitzbergensis described above (cf. PI. 2, fig. 11). They show, how¬ 
ever, a coarser sculpture with sharper striae. In one of them I also observed that on 
one side — probably the medial one — there was a smooth surface close to the basal 
edge of the crown. It was also evident that the striae with their basal ends close to 
the smooth surface were split up into fine branches that formed a network. — On 
teeth of this type the root seems to be fairly high. 
Finally there is also a fragment from the middle part of a tooth (PI. 1, fig. 20) 
which in its general features resembles the teeth P. 98 j and P. 100 among those 
described above as belonging to A. spitzbergensis (cf. PI. 2, figs. 18, 19). It has, however, 
a stronger transversal crista and the striae of the lateral side are considerably coarser. 
A further characteristic of this tooth is that the striae of the lateral side send out 
Text fig.' 6. 
Acrodus scaber n. sp. 
Tooth from a specimen 
belonging to Professor 
Dr.W. Salomon of Heidel¬ 
berg. Magnification 20/1. 
