42 



Dansk Botanisk Arkiv, Bd. 2. Nr. 2. 



It is upon this species especially that J. Agardh has based 

 his new genus Gymnosorus, as according to his idea the sori should 

 have no indusium. As pointed out by Sauvageau this is quite 

 wrong, a well developed indusium being present (see Fig. 25 a). 



On the whole I can confirm the observations of Sauvageau. 

 In the West Indies I have found the plant in deep water only 

 and in the Indian Ocean M me Weber has dredged it in depths 

 from 15 to 150 meters ; Sauvageau on the other hand found it 

 in shallow water. 



I have mostly found the erect form ; decumbent, creeping 

 specimens occurred but they were not so firmly attached to the 

 substratum as to be compared with Aglaozonia canadensis as 

 Sauvageau has done. But it should be remembered that Sau- 

 vageau collected his plant in shallow and perhaps in exposed 

 places where a firm attachment is necessary to the plant. The 

 West Indian plants were found growing upon Lithothamnion , 

 pieces of corals and similar bodies, spreading over these, and when 

 reaching the edges the free lobes turn upwards, mostly in an 

 oblique direction, seldom or perhaps never quite vertically. These 

 free lobes reach a length up to 5 cms or more. 



In transverse section (Fig. 25) we find that they are only 

 very slightly dorsiventral ; as pointed out by Sauvageau an extra 



layer of cells are found upon 

 the lower face of the erect 

 thallus. Groups of hairs occur 

 upon both sides of the plant; 

 they are usually spread as well 

 in the sterile part and some- 

 times also in the sori, now and 

 then they are arranged in rather 

 distinct concentric rings. 



The sori especially the smaller 

 ones are often elongated and 

 arranged in concentric rings, 

 but large irregularly formed 

 groups are often present. The 

 sori occur upon both sides of 

 the thallus perhaps most com- 

 monly upon the lower face as pointed out by Sauvageau. They 

 have always a well developed indusium (Fig. 25 a). As my spec- 

 imens had either old emptied sporangia or quite young ones I 

 have not been able to see the number of spores in each sporan- 



Fig. 26. Zonaria variegata (Lamx.] 



Mert. Margin of the thallus. 



(About 90: 1). 



