LOWER CAMBRIAN. o7 



Thus these lamellae seem to be the remnants of a coating which the sponge possessed, 

 whereas the fossil for the rest is perhaps a mere cast. In their consistency they hardly 

 differ from the ordinary sandstone mass. One might rather expect to find, in agree- 

 ment with the usual conditions, that such an epidermis existed on the lower side of 

 the sponge. It is therefore not impossible that the side which I have described as 

 the upper may really be the lower, although on that supposition the mode of forma- 

 tion of the fossil would be more difficult to explain. The opening which interrupts the 

 ornamentation would in that case be the surface of attachment, and the sponge would 

 thus have been attached. I have found no specimen in situ, and thus no conclusion 

 can be drawn from the natural position of the fossil. No structure can be distin- 

 guished in the interior. Thus the generic position remains uncertain, even if it be 

 assumed that the hemispherical side was the lower, and that therefore the sponge was 

 free. The species usually differs considerably from the typical species ol the genus 

 Astylospongia, but it seems still more difficult to unite it with any other of the genera 

 above described. In all probability it ought rather to form a genus by itself, but to 

 establish such a genus now would be of little advantage, since no definite generic 

 characters can be given. 



This species is not uncommon at Lugnas. At times specimens are found lying 

 altogether loose. They have been embedded in clay slate which was detached by 

 weathering. Others remain fixed in the sandstone slabs, and in such case ordinarily 

 form groups. At Stola I found a stone slab densely studded with individuals ol' this 

 species. A loose specimen I received from Mbsseberg. 



Dr. Linnarsson's reference of the species to the Spongise was, as noted 

 by Dr. Nathorst, opposed by M. Barrande, Prof. G. Lindstrom, and Dr. Ferd. 

 Roemer, and was finally given up by Dr. Linnarsson. 1 



Dr. Nathorst, in his memoir of the Cambrian medusa?, described this 

 species as follows: 



A species probably belonging to the craspedote medusa, family iEquoridae., with 

 disk-like umbrella 10 m "' to 00 nn " in diameter; wide mouth, like that of JEquorea or 

 Mesonema, taking up about half the transverse section of the body; radial canals 

 many, probably 130 to 150, single (or sometimes branching toward the edge); gonads 

 with string-of-pearls appearance all along the under side of the radial canals. 



The species is illustrated by a reproduction of photographs of a large, 

 finely preserved specimen and a small slab retaining the impression of the 

 lower side of several individuals. These certainly appear to be different 

 from the form described as Medusites favosus; and it appears that Dr. Lin- 

 narsson illustrated two species as the type of M. radiata. His fig. 16 corre- 

 sponds to the described type; and fig. 15 is the form taken by Dr. Nathorst 



1 Kongl. svensk. Vet.-Akad. Hanill.. Vol. XIX, No. 1, p. 6. 



