3 G. LINDSTRÖM, THE ASCOCERATIDE AND THE LITUITIDA. 
the bottom of the septum of the truncature and is directed towards the ventral side. 
Generally it is only its superior side which in longitudinal sections is seen protruding 
into the siphuncle of the Ascoceras (fig. 24 a). The other has coalesced with the bottom. 
The siphuncle of the Ascoceras proper consists of four elements rapidly decreasing in size 
upwards. The first is longer than the following three, and it is much longer than broad, 
quite in contradistinction with other species, the ratio between length and breadth being 
as 4: 3. In all specimens which have been studied it has, moreover, a peculiar fea- 
ture, difficult of interpretation. Interiorly on the middle of the side of the hollow (fig. 
22 a) there is seen in a longitudinal section an ingoing duplicature, sharp and pointed on 
its ventral side, blunt on the dorsal. This duplicature continues all round the walls of the 
first element of the siphuncle, as seen in other sections (fig. 19, 20), and is most prominent 
on the ventral side. It is as if this first element had been beginning to divide into two, 
though the division never had been completed. Now there is always a septum in connec- 
tion with such a duplicature, which in reality only is its continuation. But in this spe- 
cies it has not been found. That this feature is of some important significance is evident 
by its recurring not only in all specimens of this species which have been sectioned, but 
also in the two next species. Can it be interpreted as the first vestiges of a second 
septum, like that in Asc. fistula? Or is it not rather to be regarded as a useless rem- 
nant from a former second septum? 
The following three elements are flat and broad, more so than in other species. In 
the specimen with the additional septa the siphunele assumes again the shape it had du- 
ring the Nautiloid stage, with tubular elements enclosed in strong walls, connected with 
the large, downward curved necks of the septa. 
Dimensions: Length 37 millim., dorsal-ventral diam. 10 millim., minor diam. 7 
millim. In this species the difference in size between full grown shells is more prominent 
than in others. Small sized adult specimens measure in length 30 millim., d. v. diam, 
8 millim., minor diam. 35. 
This species resembles as to its ornamentation so nearly Glossoceras gracile as some- 
times to be mistaken for it. Hence its specific name. It differs, however, on closer in- 
spection not only in exterior form, the neck is more straight and large, the sigmoid septa 
quite different and, moreover, there is the peculiar duplicature in the siphuncle. 
13. Ascoceras sipho n. 
Pl. V' fig. 35-42. 
Specimens of the Ascoceras stage have becn obtained from Sandarfve kulle, Linde 
klint, Löjsta klint and Ljugarn. 
Shell elongated, nearly of the same width the whole length, tubular, only slightly 
laterally compressed, regularly curved, dorsal side concave, the ventral one convex. Neck 
long, nearly a third of the total length, only a little narrower than the rest of the shell. The 
ornamentation consists of transverse, imbricated lines. There are five sigmoid septa, which 
are much narrow in the middle of the shell. The duct from the Nautiloid siphunele is oblique. 
