60 FOSSIL MEDUSZ2. 
immersed in water, made impressions in the mud upon its bottom, and that 
after the plant itself had been dissolved the impressions filled with sand. 
Several fine illustrations accompany Dr. Linnarsson’s paper. 
In 1871 Dr. Linnarsson published a description of Hophyton linneanum 
and FE. torelli, stating that he had collected a large number of fine speci- 
mens, but that they threw no new light upon the nature of the fossil. In 
his description he says: 
The conjecture which I previously put forth regarding the mode of formation of 
the fossil has now been fully confirmed, since I had occasion to see it in its natural 
position. It always occurs on the lower side of the sandstone slabs, and if one suc- 
ceeds in detaching a piece of the underlying clay-slate without crumbling it, he will 
tind on it the corresponding impression, or the form in which the cast was made. In 
the depressed lines, which here correspond to the raised ridges on the fossil itself, 
there is often seen a row of fine depressed dots. 
In 1874 Dr. Nathorst, in an essay on some supposed fossil plants, stated 
that Eophyton must be regarded as a track of some kind, and that tracks 
agreeing with it are formed on the present seashores by plants driven about 
in the water. He made experiments and obtained striations on coarse sand 
and also on fine clay, and on the latter reproduced the relief of the trails by 
taking casts with fine plaster. He found, on comparison, that Eophyton 
agreed with the artificially made trails in the minutest details. In his clas- 
sical essay on traces of some invertebrate animals, ete., and their paleonto- 
logic significance, a full description of the mode of occurrence of Eophyton 
is given, with the statement that it occurs under the same forms from the 
Cambrian at least up to the Trias, and that all the forms under which it 
occurs are found on the seashores at the present time. He says, further, that 
it is evident that similar tracks might be produced by animals, supposing 
those animals to have fringed appendages that trail over the bottom. “The 
branching arms of Cyanea capillata, on experimentation, gave rise to Kophy- 
ton that could not be distinguished from those produced by plants.” In 
closing his remarks, Dr. Nathorst states that his interpretation is fully sup- 
ported by Linnarsson’s observations.' Casts in plaster of two trails made 
by fine alge, and also a fragment of Eophyton, are illustrated to show that 
they are essentially identical. 
In an essay on Impressions of Medusze in the Cambrian Strata of 
Sweden, Dr. Nathorst refers to having pointed out that Eophyton may 
| Ofversigt k. Vet.-Akad, Férhandl. 1873, No. 9, 1874, p. 44. 
