ERIK A : SON STENSIO 
e. g. the teeth P. 98 c and P. 98 d of A. spitzbergensis and the tooth that Miss Wemple 
(1906) has described from the Triassic of Western America under the name A. alexandrae. 
Geological occurrence and localities. — The i 3 teeth P. 98a- — m were found 
by Dr. J. Oppenheimer during the excursion of the Geological Congress at Spitzbergen 
in 1910 and were kindly handed over to the Palaeontological Institute of Upsala. A ccor¬ 
ding to the labels they come from the lower Saurian horizon, Middlehook, which seems 
to indicate that they were either collected on the mountain that is called Mt Tschermak 
on de Geer’s latest map or on Mt Congress. The teeth P. 99 a — e and the tooth P. 100 
were found in the bone-bed 33 m above the fish level at Mt Viking. No details are 
known as to the circumstances under which Hulke’s type-specimen was found. 
The teeth from Horn Sound were found by Hoel and Rovig in a bone-bed 10 m 
above the boundary towards the Carboniferous. The locality is at the north-east corner 
of Horn Sound. 
Acrodus vermiformis n. sp. 
(PI. 2, figs. 20, 21.) 
Under the species name A. vermiformis I group at present only two teeth (P.9811, P. 101). 
The best and most completely preserved of these (P. 101) is relatively long and 
low (PI. 2, fig. 20). In its present state of preservation with one end (portion) broken 
off it is about 24 mm long, while its greatest height does not amount to more than 5 mm. 
Both the crown and the root are straight when seen from the medial or lateral 
side. Regarded from the crown, they are both, on the contrary, somewhat bent in the 
way shown in PI. 2, fig. 20 a, i. e. the median part is weakly convex at the medial side, 
the two ends, on the other hand, at the lateral side. The curvature of the root is 
weaker than that of the crown. 
The crown has the same width almost throughout its entire length. At the median 
part it is higher than towards the ends, but the difference is, however, rather slight. 
A longitudinal crista which for the same reasons as in A. spitzbergensis, ought to be 
termed the primary longitudinal crista, seems to have been developed throughout the 
entire extent of the crown. It is somewhat stronger than in A. spitzbergensis and is 
characterized especially by its irregulary sinuated course. On both the medial and the 
lateral side of'it there is at certain parts a discontinuous secondary longitudinal crista 
that is also rather strong and that resembles in its development the one on certain 
teeth belonging to A. spitzbergensis, such as, e. g., P. 98j and P. 98 m, i. e. the striae 
running from the basal parts of the crown towards the longitudinal crista in the species 
in question are attached to each other in groups at their distal ends and form a number 
of short cristae in the longitudinal direction of the crown. Of these latter cristae each 
in its turn runs for a bit towards the middle part of the tooth, to finally fuse with the 
primary longitudinal crista, or possibly, in the case of the middle part of the tooth, 
with the transversal one. This latter crista most closely resembles in its development 
the similarly situated one on the tooth P. 98 h (PI. 2, fig. i 3 a) in A. spitzbergensis, but it 
is coarser and has a ramification that differs in its details. 
Besides the longitudinal and transversal cristae the sculpture of the crown consists, 
as has already been pointed out, of the same sort of striation as was found in A. spitz- 
