48 FOSSIL MEDUS. 
medusa on account of its pentameral symmetry. Replying to this, Dr. 
Nathorst stated that he had studied the recent forms, Awrelia aurita and 
Cyanea capillata, in large numbers, and found in the latter five-sided as 
well as four-sided symmetry. It is more rare in A. aurita, though both 
three-sided and five-sided symmetries exist, in addition to the usual tetra- 
meral symmetry.’ 
From the evidence adduced by Dr. Nathorst, and from a comparative 
study of both the fossil and the recent forms, I am led to regard the Swedish 
Lower Cambrian fossils as evidences of the presence of medusz in the 
Lower Cambrian seas of Sweden. 
It may be doubtful whether Dr. Nathorst’s interpretation of Eophyton, 
as made up of trails produced on mud by meduse, is correct, but it is quite 
probable that in some instances they have originated as he suggests. As 
regards others, however, I think there is little doubt that they owe their 
origin to the trailing of alge over the bottom. On this account I have 
inserted a description (pp. 59-65), rather freely illustrated, of the fossil 
forms that have been referred to Eophyton. 
In an article on ‘Illustrations of the fauna of the St. John group, 
No. V,” Mr. G. F. Matthew quotes the descriptions of Medusina princeps, 
M. radiata, and M. costata from Linnarsson. He also describes five forms 
of what he considers to be trails or the imprints of tentacles of meduse, 
under the generic name of Medusichnites.’ | 
Through the courtesy of Mr. Matthew, I have examined the original 
specimens, and I find that, with possibly the exception of fig. 1 of his Pl. 
XIII, all of the varieties of Medusichnites might much better be referred to 
markings of inorganic origin. I have seen large areas of Lower Cambrian 
shales in Rensselaer County, New York, covered with markings like those 
shown by his fig. 4 of Pl. XII and fig. 1 of Pl. XIII. These were studied 
in connection with the investigation of medusa-like trails, and the conelu- 
sion reached was that they could not have had such an origin. 
In order that the student may have the means of comparison, I have 
introduced photographs of some of the typical specimens described by Mr. 
2Trans. Royal Soc. Canada, Vol. VIII, 1890, sec. 4, pp. 143-146, Pls. XII, XIII, fig. 1. 
