54 
Fig. 
G. LINDSTRÖM, THE ASCOCERATIDA AND THE LITUITIDA, 
PIAEE VIR 
Choanoceras mutabile n. 
1. Specimen from Samsugn with seven septa, of 
which five are incomplete. 
2. Same specimen from the side of the lacunose 
septa, a little sectioned to show that the 
septa join each other as in Ascoceras. 
3. ÅA specimen showing transition from the ini- 
tial stages to the later with one incomplete 
septum. 
4. Younger specimen from Samsugn without la- 
cunose septa and with more cylindrical si- 
phuncle elements. 
5. Surface ornamentation of the same. 
6—38. Fragments with cylindrical elements of the 
siphuncle. 
9. Smallest specimen from the shore of Boge, 
with four septa and cylindrical elements of 
the siphuncle. 
10. Ornamentation of its surface. 
11. Another small specimen with only three septa. 
12. Specimen from Follingbo with nummuloid ele- 
ments of the siphuncle and no lacunose septa. 
13. a. The exterior shell, b. The inferior side of 
the septum. At X small pits. This figure 
is magnified from the septum marked X in 
fig. 16 and likewise in fig. 12. 
14. Part of the shell (a) to show the interior im- 
pressions of its wall (6) and the pits on the 
upper edge on the inside of the septum (c). 
15. A section to elucidate the position of the 
just mentioned impressions: Db. inside of 
the shell, c. inside of the septum. 
16. Longitudinal section of a shell, showing the 
relative position of the septa and the wall; 
Xx. the point where the pits, figured in fig. 
13, are situated. 
17. Fragment showing how the truncation takes 
place or how an inferior part of the shell 
is broken away from the rest. 
18. An unknown Cephalopodous shell from the 
limestone of Slite with funnelshaped septa; 
a. the two uppermost septa magnified. 
19. The same two septa sectioned to show the 
prolongated funnel. 
20. A schematic representation of these septa. 
21. Ophidioceras reticulatum ANG. from Othem, 
Samsugn; a. part of 
it to show ornamen- 
tation, h. ornamen- 
tation of largest 
. 22. Ophidioceras reticulatum ANG. 
whorl — still 
magnified. 
The ventral 
keel of the same. 
Section of a speci- 
men, same loc. 
Innermost = whorls 
of same = section. 
Transverse section, 
showing the position 
of the siphuncle. 
Another specimen, 
same loc. 
Transverse — section 
of all whorls. 
Details of ornamen- 
| tation. 
29. » » A third specimen 
from Samsugn. 
Tranverse section. 
Section of specimen 
with narrower whorls 
from Fårö; a—b de- 
tails of siphuncle 
and septa. 
Ventral keel ofspeci- 
men from Follingbo. 
Transverse section 
of largest whorl to 
show the form of 
the keel. Follingbo. 
34. Ophidioceras rota n. Largest specimen from 
Sandarfve kulle. 
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34 a—ec. > » Details of its ornamentation. 
SÖK » » Ventral keel. 
36. ) » Transverse section of spe- 
cim. fr. Linde kliut. 
37. » » Longitudinal section of spe- 
cim. fr. same loc. 
38. Ophidioceras reticulatum ANG. Nucleus of spe- 
cimen from Grogarn 
with impressions of 
the inside of the 
shell; a. magnified, 
b. seen edgewise. 
39. » Transverse section 
of the whorl. 
40. , Keel of the nucleus, 
thestriae being nearly 
horizontal. 
