Review of Recent Geological Literature. 59 
and tracks occurring in the sandstone in which the MedusjE are found. 
Dr. Torell, the first describer of these Medusan remains, referred 
them to corals. Dr. Linnarsson, who followed in their interpreta- 
tion, thought they were sponges. Finally Dr. Nathorst, who went 
into a very careful study of the object, concluded they were MeduscC, 
and referred them to the genus Medusites, now changed by Mr. Wal- 
cott to Medusina. These Swedish fossils were thought to be casts 
of the gastric cavity, etc., of Discomeduss which had been thrown 
upon a sandy shore, and partly filled with sand, forming a mold of the 
interior, before they perished. Three species were described by the 
Swedish naturalist from these Lower Cambrian rocks. 
In connection with the account of these remains Mr. Walcott gives 
a history of the discovery and elucidation of the curious fossil Eophy- 
ton, so abundant in some portions of the Cambrian rocks. Eophyton 
iiad been described by Dr. Torell in 1868, two years previously to the 
account given by him of the Medusan remains, and since then has 
been referred to and commented on by various authors. The first 
describer and Dr. Linnarsson thought it was a plant of higher or- 
ganization than a seaweed. Later observers, as Nathorst, Dawson 
and Dames, regarded these markings as made by Medusae or other 
animals. Saporta goes back to the old idea that they are prints of 
sfaweeds, though he admits that some are possibly trails of seaweeds. 
Mr. Walcott concludes that it is quite probable such markings may 
be produced as Nathorst has suggested by Medusa;, though he thinks 
there is little doubt that others owe their origin to the trailing of algje 
over the sea bottom, especially in shallow water, where the tide was 
running out. He has observed such trails many feet in length in direct 
lines, without a bend or interruption, made by drifting algse. 
Nearly a dozen varieties of Eophyton have been described by vari- 
ous authors as species. 
About thirty pages of this work are devoted to a description of 
the Jurassic and Permian Medusae of Central Europe. Mr. Walcott 
has conferred a boon on American students by giving full descrip- 
tions of these fossils with admirable figures and analyses of the struc- 
ture, mostly taken from Hasckel's and Brandt's studies of the species. 
Half of the Jurassic forms are referred to two suborders of the Disco- 
medusse, viz.: Semostomae, Agassiz,and Rhizostomae, Cuvier; the 
other half are referred to Medusites, as not being capable of classifi- 
cation in the suborders above named. Twelve species are described, 
all of which, except one, appear to have been determined by Hasckel. 
Only one species, M. atava, has been described from the Permian. 
Among objects classified as "Incertas sedes," are the Medusae of 
the Cretaceous of northern Germany, of which a few species have 
been described, and which in this work are referred to the sponges; 
and G. F. Matthew's genus Medusichnites proposed for tracks sup- 
posed to have been made by the tentacles of Medusae. Of these trails 
it is thought by Mr. Walcott that one which he figures may have been 
{•roduced by Medusae, all the others he thinks are of inorganic origin. 
