KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 23. N:o |2. 5 
Bryozoa, had fixed themselves and grown luxuriantly, which of course could not possibly 
have been the case, if the substratum had not already then been as hard as we now find 
it. In the same way, the large siphuncles of the Actinocerata are often found detached 
and covered with Corals and Bryozoa. The filling up of the air chambers must have oc- 
curred after the death of the animal and since the shell had been washed ashore or lay in 
shallow water or even far later when enelosed in the solid rock and participating in 
the metamorphic changes which this underwent during the succeeding periods. It is not 
to be confounded with the depöt organique, which, smaller in degree, took place during 
the lifetime of the animal. 
In most species the shell has been exceedingly thin, even in the largest, scarcely 
attaining a thickness of half a millimetre and in a few of the largest Orthoceratites it 
reaches at the highest two millimetres near the aperture. What wonder then that rela- 
tively so few have been preserved with the shell and that in some localities we only meet 
with the nuclei and faint traces of the shell? This is then often wrinkled and ecrumpled 
through the weight of the superimposed strata. As a rule the shells are better preserved 
in the limestone beds and entirely wanting, or nearly so in the marly shale beds. ”The in- 
filtrated mass is commonly calcareous spar, which in the way, as BARRANDE has so well 
described, has crystallized at the same time from both sides of the septa and met in the 
centrum of the airchamber, thus causing the false appearance of adventive septa. In a 
few instances patches of fleshy red baryte have been formed in Orthoceratites found in 
shale near Wisby and even of black fluor calcium. The shells which lie in the limestone 
are naturally transformations of the original ones into calcareous spar. Ås to some found in 
the shale beds there may be an exception and the original shell at least in some respect pre- 
served. So for instance with some of the Phragmocerata of the shale. In them it has a 
glossy, yellow-brown or blackish hue and the colour pattern is very distinct, coming near 
to the angular, black bands that prevail in the recent Nautilus. Also in some Orthocera- 
tites from Östergarn the colour pattern is very well preserved and consists of narrow, 
whitish, longitudinal stripes. The pearly lustre is preserved on the inside of the shell 
remarkably well in a few Orthoceratites. 
There is a great variation in the size, some having only one or a few millimetres 
in diameter, and others again are 'gigantic. The largest ever found is from the limestone 
of Follingbo and must, when entire, have attained a length of 2 metres, having in the aper- 
ture a diameter of 12 centimetres. 
It is self evident that the specimens very seldom are found so free as to be at 
once fit for delineation or description. Only by employing great care they may be ex- 
tracted from the rock, and then they must be cleaned and prepared from out the enclo- 
sing stony matter. 
The most remarkable localities in the uppermost limestone, from which the greatest 
number of species has been collected, are in order from north to south: Sändvik near 
Fårösund, Samsugn and Klints i Othem, Storugns near Capellshamn, Bjers in Heinum, 
Fohle, Follingbo, Linde and Sandarfve, Lye, Ljugarn, Hamra and Hoburg. 
Owing to the presence of large masses of Stromatopore and large Corals, the banks 
of Cephalopoda in these strata are seldom regularly stratified. They form rather a massive 
