BIHANG TILL K. SV. VET.-AKAD. HAXDL. BAND 7. N:0 5. 5 



with Annelid remains, and these animals appear to have favour- 

 ed the soft muds of the sea bottom which are now hardened 

 into calcareous shales and flags. I also notieed that many of" 

 the rock-surfaces are covered with irres:ular track-like 

 inarkings which may have been produced by the burrowing 

 of these creatures in the mud. 



In addition to these specimens from Fröjel, I also obtain- 

 ed numerous others from a small quantity of decomposed 

 shale from the neighbourhood of Wisby, which Prof. Lindström 

 very kindly gave me. This I carefully prepared by washing 

 und sifting, and then examined with a strong lens. To my 

 great satisfaction this material proved exceedingly rich in these 

 small jaws, there was a great variety of forms, and they are 

 preserved in such perfect condition, that their characters can 

 be as readily studied a-s those of recent annelids. 



In appearance the fossil annelid jaws from Gotland re- 

 semble, in every respect, those from the corresponding strata 

 in North America and England; they are of a blackish tint, 

 and the surface is smooth and polished. 1 have not been able 

 definitely to determine the present chemical constitution of 

 these small bodies, biit it appears to consist of mineral com- 

 ponents, in which carbonate of lime is absent, for nitric acid 

 produces no effect on them. It is not improbable that the 

 original chitin has been, in part at least, replaced by carbona- 

 eeous material. 



These jaws are now scattered irregularly throughout the 

 rock, entirely detached from eachother; in no single instance 

 have I discovered the different plates which constitute the jaw- 

 apparatus of the animal in their natural relative positions, 

 although this occurs in the case of the fossil Jurassic anne- 

 lids from Solenhofen which have been described by Prof. 

 Ehlers [Paleontographica Bd. 17 p. 145.] But though thus 

 detached, these fossils give no indication of having suffered 

 from abrasion and transport, and it seems to me that the disturb- 

 ance in position which they have undergone may not impro- 

 bably be attributed to the small ostracoda abounding in the 

 same beds, wdiich, by preying upon the soft parts of the anne- 

 lid after its death, and thus consuming the miiscles which 

 held the jaws in position, rendered them liable to be separa- 

 ted from each other by the slightest movement of the water. 



