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ai-e for the greater jiart vevy small ; tliev are not easily distin- 

 guished. Among tliem are l)igger transparent ones. The diameter of 

 these latter grains is at most Vs millimetre; they are mostlv arranged 

 in parallel planes, in consequence of Avhich an indistinct laver-like 

 construction becomes visible on the vertical sides. On one of the 

 horizontal sides tliere are still parts of a i'ew thin lavers. In the 

 stone are a great many small cavil ies, 'whicli ^vere formerly e^'idently 

 filled with organic remains. 



On both of the horizontal sides we find remains of Tribolites. On 

 one of them the most iuiportant are an off-jirint of a mid-shell al)out 

 8 millimetres long, and a stone-kernel 10 millimetres long, part of the 

 shell of which, turned into iron-hydroxide, is still present. On the 

 other horizontal side is found the front part of an off-print of a much 

 larger mid-shell, wliicli oiicc had a length of about 15 millimetres. 



Undoubtedly these remains, which in many respects resemble each 

 other, have come from the same kind of Tribolites. The two first 

 mentioned are remains of younger individuals ; the other belonged 

 to a moi-e or less full-grown sj^ecimeu. 



With the younger individuals the glabella was convex, its length 

 surpassed its breadth a little, its breadth diuiinishing towards the front. 

 On the front side the glabella is somewhat rounded. On the plaster- 

 cast I made of the ofF-prinl of the small mid-shell, it is clearly visible 

 that the glabella possessed at least 2 side-furrows on either side. The 

 stone-kernel shows that the neck-ring was In-oadened in the middle. 

 The cheeks were vaulted, Avhich is very clear in the stone-kernel 

 especially. Very characteristic is a deep furrow enclosing the glabella 

 in front and lieing continued on either side on the cheeks, where it 

 broadens and becomes less deep. Before this furrow is a vaulted })art, 

 which does not turn down. The front-edge of this part is on about 

 the same level with the back-edge, whilst its height is equal to that 

 of the glabella. Iji the off-print of the little mid-shell the glabella is 

 472 millimetres in length, and the part in front of it nearly 3 milli- 

 metres in breadth. 



It is apparent from the off-print of the mid-shell of the more or 

 less full-grown animal, which mid-shell is only partly exposed to 

 view, that the glabella and that part of the mid-shell which is in 

 front of it, Avhich does not turn down here either, are less \'aulted, 

 and that the furrow separating the two, is less deep. Here are no 

 side-furrows to be distinguished on the glabella. 



With the assistance of the sciejitific works I dispose of, I found 

 that these remains are most like those of Arionellus primaevus Brögger, 

 of which up to this time only mid-shells Imxe been pictured and 



