KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 23. N:o |2. 23 
near the ventral side and consists of straight, narrow tubes which continue without inter- 
ruption through the whole shell and some of the elements have a length of 11 millim:s. 
It is true that this Nautiloid stage has not been found in immediate connexion with 
the Ascoceras stage, but it may be inferred from its close similarity in structure with 
specimens of other species found adherent to the Ascoceras from other localities that the 
deseribed Nautiloid and the following Ascoceras belong to the same species. The simi- 
larity of their surface ornamentation, the position of the siphuncle and the circumstance that 
both are found together in the same rock and nowhere else, strengthens this assumption. 
2. The Ascoceras stage. 
The shell is long, slender, cylindrical, wider near the truncated end. At the top of 
the third sigmoid septum the shell forms a slight, necklike constriction, which is bent in 
an obtuse angle. The inferior, broader portion which contains the septa, is ovate in sec- 
tion, the superior, necklike part is circular. 
The truncated end has the same shape as the septa of the Nautiloid stage, and is 
strongly lined with new depositions from within probably before the decollation and has 
thus attained nearly the same thickness as the shell. The aperture of the siphuncle is 
closed uniformly with the same deposition. 
The outside of the flasklike, inferior part of the shell is regularly fluted by trans- 
verse, narrow ribs, 14 on a length of 5 millim:s curved downwards on the ventral side. 
Around the superior cylindrical portion they are fine and more numerous. In a section 
the fine strie, which cover them, form regular, but bluntly serrated lines. There are in the 
rule five septa, two regular and three sigmoid ones. In some specimens there is moreover, 
in the deep saddle of the third sigmoid septum a fifth short additional septum of the re- 
gular type. When largest the sigmoidal septa are 6 millim:s broad near the outside, and 
only 3 millim:s interiorly, the diameter of the shell being there 7 millim:s. One specimen, 
Pl. I fig. 27 & a, shows the peculiarity that the first and second sigmoid septum do not 
join in the interior of the shell and that thus the second is quite as complete as the first. 
On plate TIIT are given schematized figures (9—11) of the sigmoid septa of this species. 
In fig. I they are seen together, front view from the ventral side, in their natural position 
and in figs. 10—117 the third sigmoid septum alone is represented as if dissected out, and 
seen, fig. 10, in front with its large lacuna, and, fig. 11, in lateral aspect. 
From the formation of a fourth additional regular septum on the bottom of the 
body chamber above the sigmoid ones may be concluded, that the animal continued to 
occupy the whole length of that chamber even after the completion of the sigmoid septa. 
The siphuncele consists of short nummuloid elements which increase upwards in 
breadth, if not in volume, the second being the largest and the third the broadest of 
all. The septal necks are short. 
Length 41 millim., breadth 8 millim., shorter diameter 5 millim. 
4. Ascoceras pupa n. 
RADE 
Distribution. From the uppermost limestone of Linde klint and Sandarfve kulle. 
Only the Ascoceras stage is known. 
