326 SUMMARY OF CURRENT RESEARCHES RELATING TO 



whicli corresponds exactly with the ' Zopfen ' of the so-called 

 ' Zopfplatten ' ; Idothea baltica forms Prolichnites ; a Planariau 

 makes a flat, ribbon-like track ; Montacufa makes clentated impres- 

 sions, which closely resemble Graptolithcs ; an unknown animal 

 makes a regular, zigzag, serijentine mark ; a piece of an alga drawn 

 over mud produced a streaked mark which corresponded exactly with 

 what is described as Eophi/ton, and which has hitherto been considered 

 a plant. Similar impressions were made by the tentacles of Medusae. 

 Drops of water falling upon mud covered with a thin stratum of 

 water produced remarkable, regular, wheel-shaped figures, which at a 

 distance recall Medusae. An earthworm made an imjiression very 

 similar to what is usually described as Spirophyton, and hitherto con- 

 sidered an alga. This was produced in the following manner : — In 

 creeijing over the wet mud, the worm suddenly came to a stand ; and 

 while its hinder part remained motionless, the anterior was stretched 

 out, while it at the same time bent itself so much to the side that 

 its head was brought close to the other extremity of the body. 

 After the front part had thus been stretched to its fullest extent, it 

 was suddenly drawn back again, without, however, altering the 

 position of the hinder part and the head. 



A complete review is also given of the marks of animals found in 

 the Swedish rocks, and a catalogue of 129 publications in which these 

 marks are described and illustrated. At the end of the list is a work 

 by Saporta and Marion, which appeared about the same time as 

 Nathorst's, with the title, 'Levolution du regno vegetale, les Cryp- 

 togames.' In this the authors endeavour to explain, according to 

 the Darwinian theory, the gradual evolution of plants from the earliest 

 stages, through the series of geological formations to the present day. 

 Unfortunately " (it is said), " the greater number of fossil remains 

 regarded in this book as plants are in reality the marks of worms."* 



Nathorst has also published a second interesting paper f on the 

 origin of particular marks, which Herr Fuchs abstracts as follows : — 



" Some time ago peculiar unknown bodies were found in the Cam- 

 brian strata of Lugnas in Sweden, which were described by Torell 

 and Linnarson under the names of Spatangopsis costata and Astylo- 

 spongia radiata. These bodies are in the form of 4-5 rayed stars or 

 4-5 cornered pyramids, which either lie free in the mud, or with 

 the under surface adhering to the rocks, or form only an impression 

 on a slab. Between the rays and corners are occasionally to be seen 

 crescent-shaped projections. When Nathorst was at Oeresund in 

 1880, it happened that a large number of Aurelice were thrown on 

 the shore. The animals all lay with the mouth downwards, and 

 when he took one up he observed that it had sunk in the soft ground 

 by its own weight, and that its gastrovascular system had made a 

 star-like impression, showing the most striking resemblance to the 

 so-called Spatangopsis. He then followed up the matter further, 

 partly by making impressions of various Medusce, and partly by 

 filling up their gastrovascular system with jtlaster, and so obtained a 



* A rather too sweeping assertion.— Ed. 



t Handl. K. Svenska Vetens. Akad., xix. (1882). 



