EXPLANATION OF PLATES. 
Where nothing special is stated, the type specimens of the figures given here belong to the 
Palaeontontological Institute of Upsala. The great majority of the photographs where taken by 
Miss Aina Laurell of Upsala. 
There were many great difficulties in the photographing and, in spite of great efforts, it was 
not possible to obtain as good figures as was desirable. This was due in the first place to the 
state of preservation of the material. The specimens were often very much broken and large pieces 
were missing here and there. The bone substance was sometimes dark-coloured, little differentiated 
from the rock, while sometimes, on the other hand, it was partly or entirely blue in colour because 
of transformation into vivianite. 
Another reason why the figures given here do not satisfy all the demands one is entitled to 
make on them is that the photographic-apparatus at my disposal was partly of a very primitive 
and deficient nature. 
When nothing is said to the contrary the figures show the natural size. 
Plate i. 
Fig. i. Hybodus rapax n. sp., tooth (P. 41b); a, in medial aspect; b, in lateral aspect. 1 j 1 . 
» 2. » » » » » (P. 4ia)\ a, » » » b, » » » 1 / 1 . 
» 3. Hybodus sasseniensis n. sp., tooth (P. 39 a ); a, in medial aspect; b, in lateral aspect. ! / 1 - 
4. » 
». * » 
* ( p - 39 b ); a, > 
* 
b, » 
» 2 /r 
5- 
» » » 
» ( P-39 C )Y a, » 
» » 
b, ». 
» 2 /r 
6. » 
» » » 
» {P- 39 d) > a, » 
» » 
b, » 
» 2 /f 
7- » 
» » * 
» (P- 39 e l a, » 
» » 
b, » 
» 2 /i. 
8. » 
» » » 
* (P.38); a, » 
» » 
b, » 
» 2 /r 
» g. » » » » » (P. 633); in lateral aspect. 4 / r Below the tooth there is 
seen a dermal denticle. 
» 10. » > » » » (P. 40 ); in lateral aspect. 1 f 1 . 
» 11. Hybodontid selachian; basal plate of cephalic spine (P. ^5r); a, seen from the external surface; 
b, seen from the basal surface. 1 / 1 . 
» 12. Genetically indeterminable selachian; basal portion of fm-spine (P. 44) in lateral aspect. |/ r 
» i3. » » » (the same species as in the preceding figure); anterior 
portion of fin-spine (P. 43) in lateral aspect. 2 / r 
» 14. Detached dermal denticle (P. 884), probably from a hybodont selachian. s / 2 . 
» 15. Hybodont selachian; portion of fin-spine (P. 102) in lateral aspect. 1 / v 
» 16. > * » » (P- 883) » » » 7r 
» 17. » » fin-spine (P. 282) in lateral aspect. 1 / 1 . 
» 18. Probably hybodont selachian; portion of fin-spine (P. 42). a, in posterior aspect; b, in lateral 
aspect. 1 / 1 . 
» 19. Generically indeterminable selachian; fin-spine ( P.35 ); a, in posterior aspect; b, in lateral 
aspect. 2 / 1 . 
