KONGL. SV. VET. AKADEMIENS HANDL. BAND. 19- N:0 6. 165 



The inside is bordered by an annular callosity (tig. 18) and the enclosed area 

 is glossy, sculptured by numerous, microscopic striaä, concentric in a zone nearest the 

 börder, in the centre spirally curved, where also the surface is somewhat excavated. 

 On the outside the numerous coils are rather flat and broad, as shown in tig. 16, on 

 their inferior face ornamented with some fine, concentric striaj below a larger one. 

 Their appearance in a transverse section is given in fig. 22, to be coinpared with that 

 of Oriost. globosum in fig. 25. The lobes of the sectioned coils are broad and short, 

 with low divisions between thein and their tops only finely jagged by the parallel lines. 



This shell, as well as its operculuin, has been found most numerous in the lower 

 limestone beds of Östergarn, also in Ardre, Gothera, in the Rhizophyllum beds uear 

 the church of Lau, and in the limestone beds of Lindeklint. 



It is distinguished from its congeners through its more richly sculptured keels, 

 nearly smooth interstices, only finely sculptured and by the peculiar operculura. 



From the subjacent shale beds, such as they are in the canal of Wisne myr in 

 Fardhem, I have obtained specimens of a shell nearly resembling O. coronatum. In 

 some, however, the sculpturing is intermediate between this and O. funatum. 



From Martebo numerous specimens of an operculum have been obtained, which, 

 however deviating, still, through certain common details of shape, prove to be related 

 to the operculum of Or. coronatum. Pl. XVII figs. 32 — 35. The shell to which it 

 has belonged is for the present not known, though the operculum is far from being 

 rare. In its form it resembles as nearly as possible the modern artillery projectiles, 

 being elongately conical in outline, fig. 32. They commonly have the same height as 

 the diameter or sometimes higher. Some are constricted transversally along the median 

 line. The dimensions of three specimens are: 



1) Diam. 13 mill. Height 16 mill. 



2) » 13 « » 11 » 



3) » Il » » 10 » 



The coils on the outside are directed obliquely outwards or nearly parallel with 

 the diametral axis of the operculum and are considerably shorter and broader than 

 those of Or. globosum. 



The narrow, ornamental lines which are crowded on these coils, fig. 34, are most 

 numerous and prominent on the inferior side, short and scarce on the upper half 

 of the coils. On the inner side the annular edge is prominent, the centre deeply ex- 

 cavated and the spiral distinct. A similar operculum has also been found in the up- 

 per limestone beds of Slite. 



Mr Rob. Etheridge jr has described and figured^) several opercula of which some 

 are identical with the Gotlandic. Figures 9 and 9areally represent one of the conical 

 opercula from Martebo which I once sent to the British Museum. In fig. 12 an oper- 

 culum is seen, nearly corresponding with that from Westergarn, figured in my plate 

 XVII fig. 24. Fig. 14 probably repi-esents one of the »sculptum» varieties, as Etheridge 

 also believes, though with some hesitation. But it is only the impression of the inner 



') Ann Mag. N. H, 5th Ser. vol. 7, p. 25 pl. II. 



