28 G. LINDSTRÖM, THE ASCOCERATIDE AND THE LITUITIDEZ. 
the bottom has the appearance delineated in pl. III fig. 7. Near the dorsal side the first 
septum (1.) occupies the whole space and around it the succeding septa are arranged. 
Around the siphuncle the septa are raised in a small cone. 
The septum of the truncature or the last Nautiloid septum (PI. IT fig. 18 a, pl. III f. 
J) is strengthened by depositions from the interior so as to be nearly as thick as the shell 
itself. It consists of two strata, b, the original septum, c, the larger interior stratum 
which is also continuous and common with the shell. As may be seen by fig. 5 pl. III 
the shell again consists of three strata, a, the thinner exterior one and c, the same as 
before and innermost a dark stratum formed by the sigmoid septa. | 
The neck of the last Nautiloid septum is prominent and closed by a thick secretion 
from the interior. On the interior surface round the aperture of the septum of the trun- 
cature is the same sort of basal tube, which is so characteristic to the Nautiloid. It is 
seen in a section, Pl. II fig. 18 a, Pl. III f. 17 a and also restored according to a spe- 
cimen, pl. III fig. 6. It becomes more narrow towards the apex. It is in this position 
only a structure without use, as no tubular siphuncle for which to serve as a basis, was 
ever formed, when the animal changed into the Ascoceras shape. The elements of the 
Ascoceras siphuncle are broadly nummuloid, the second being the broadest of them all. 
The septal neck around them is very small. 
Dimensions. Spec. A. Length 15,8 centim., breadth dorso-ventral diam. 31 millim., 
lateral-diam. 22 millim. — Spec. B. Length 16 centim., dorso-ventral diam. 31 millim., 
minor diam. 21 millim. 
An attempt has been made in pl. VI fig. 3 to reconstruct this the largest of our 
Ascocerata. The details are taken from the detached parts found in the same locality, 
Sandarfve kulle. But it is highly probable that the shell never has occurred in this com- 
plete shape, as there is evidence that decollation has taken place many times during the 
Nautiloid stage. 
8. Ascoceras ampulla n. 
Pl. IV fig. 1—4. 
The type specimen is from the limestone of Samsugn in Othem. 
Only the Ascoceras-stage has been found. 
Shell flaskshaped, much flattened, dorsal and ventral sides convex, the ventral more 
so. Neck short, making a fourth of the total length. The ornamentation consists of trans- 
verse strix, more dense and crowded and consequently finer near the aperture. They 
are longitudinally folded by broad wrinkles. There are four sigmoid septa, as to their 
position and shape like those of Ascoc. bohemicum. The first is the shortest and most 
widely separated from the others. 
Length 50 millim., dorso-ventral diam. 21 millim., lesser diam. 13 millim. 
This species nearly resembles Ascoc. bohemicum as to its shape and the form of 
the septa. It is, however, smaller, its ornamentation is different and it is moreover much 
flatter and more compressed in the direction of the smaller diameter. 
