toma in habit, differs from that and from all others of the genus 

 Bidyota in wanting the woolly or stupose root; in place of 

 which it is furnished with more or less abundant fibrils, issuing 

 without order from the lower portion of the frond, and attaching 

 themselves to neighbouring Algae. Had these only been found 

 on one or two individuals, I should probably have taken them 

 for a mere aberration, but finding them sufficiently constant in 

 many specimens, collected in different localities and at different 

 times, I am induced to regard them as an essential character, by 

 which the present species may be most easily distinguished from 

 others. 



As in D. dichotoma, the frond varies much in breadth, but 

 scarcely in any other respect. Our figure represents an average 

 specimen. 



Fig. 1. DicTYOTA KADiCANs, — the natural size. 2. Portion of the membrane, 

 mmjnified, to show the reticulation. 3. A cross section of the same, show- 

 ing: the internal structure. 



