KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 23. N:o |2. 39 
Deser. Whorls at most 4, commonly 3, flattened and broad, in section showing the 
ventro-dorsal diameter longer than the diameter crossing it at right angles (HFigs. 25, 
27, 30). The last whorl has grown out straight near the aperture, but none of the Got- 
land specimens has the aperture complete. The side ribs of the whorls are rather distantia- 
ted, being about three on a length of 10 millim. The shell is finely reticulated, as seen 
in the magnified figures 21a, 29 a, the transverse strix being in the exterior whorls 
sometimes stronger than the longitudinal ones (/figs. 21a—b). The ventral keel (/figs. 22, 
32, 33) is bordered by two thin edges and is sculptured by regular curves directed back- 
wards and ecrossed by longitudinal lines. 
The body chamber is long, occupying half the first whorl. The septa are regularly 
distantiated, as many as 23 in the second whorl from the outside, gently curved and very 
thin (figs. 23, 24, 31, 31la—b). The siphuncle is placed near the ventral or exterior side, 
although in some specimens a little closer to the central axis. It is slender and narrow 
and where its component parts meet the funnel of the septa, they are, as it were, stran- 
gulated (f. 31a). The siphuncele has much thinner walls than the septa. It ends blind 
against the ventral side of the initial chamber (fig. 31b). The inside of the shell has left 
peculiar traces of impressions of the mantle on a nucleus from Östergarn (figs. 38, 40). 
They consist of wavy, interrupted, imbricated lines, forming a serrated edge when seen in 
a section, being thus of a character, which returns in the Ascoceratide, as well as in 
other Cephalopoda. 
As may be seen through the figures 21; 29 and 25, 27, 30 there is some varia- 
bility as to the size and shape of the whorls, but the chief characters are retained. 
Dimensions. Largest diameter 32 millim. Breadth of largest whorl near the aper- 
ture 12 millim., thickness of the same 9 millim., average distance of septa 3 millim., 
breadth of keel 4 millim. There are dwarf specimens, full grown, with straight end of 
the last whorl, having in diameter 20 millim. and only three whorls. 
From the second Gotland species, with which it sparingly occurs in the same beds 
in Linde and Sandarfve, it is easily distinguished by its less numerous and broader whorls, 
by its ornamentation, entirely reticulate, and by its ventral siphuncle. As to foreign species 
it comes near to O. simplex BARRANDE (pl. 97 f. 1—12, vol. II pt. 1, page 184), which also 
has a ventral or external siphuncle, but more narrow whorls and the septa more irregu- 
larly distantiated. The English O. articulatum Sow. (BLAKE p. 230, pl. XVIII f. 14, 15) 
is too badly preserved to be identified with the Swedish species. The siphuncle is, how- 
ever, nearly external, but the septa are more remote from each other. 
2. Ophidioceras rota n. 
PI: VIL, fi 34—37. 
Syn. 1888. OO. rota LinpstR. List of Fossil Faunas of Sweden p. 7. 
Distribution. In the uppermost limestone strata of Mannagårda in Lye, Linde klint 
and Sandarfve kulle. 
Whorls six and a half, narrow, terete, the transverse diameter being larger than 
the dorso-ventral one (fig. 36). The end of the last whorl has grown straight, but no 
