( 80 ) 



distance or occasionally nearly to the base, the axils rather wide, 

 and rounded. Substance membranaceous, rather tender, more or less 

 adhering to paper in drying, imperfectly at the base. Colour, at the 

 base, a dark olive brown, paler upwards, pale olive green at the sum- 

 mit. Fructification forming darker concentric zones over the upper 

 two-thirds of the frond, seldom towards the base, at a distance of from 

 one to six or eight lines, the inspaces more or less matted with irregular, 

 interrupted, scattered patches. Sj)ores roundish elliptical, scattered 

 over the whole upper surface of the frond, often forming irregular 

 undulating concentric bands. 



This very pretty species is said to have been once found in the Frith 

 of Forth {Dr. Greville), but we are not aware of its recent appearance 

 there, nor do we know whether it was picked from the rocks or only 

 from the beach. Even in the south of England it is rare, and still 

 more so in Ireland ; in the south of Europe it is rather more plentiful, 

 extending nearly to the southern limits of the temperate zone. 



It has now been separated from its congener, and certainly if such 

 species as Rhodymenia laciniata, reniformis, and palmata must stand in 

 separate genera, we can see no pi-opriety in retaining the present in its 

 old position, as the structure, habit, and fructification of the two plants 

 are all diff'erent. The grouping of the spores in the present species 

 into irregular spots or zones, is quite diflferent from the regularly formed 

 sori of the next species ; and the spores themselves are still more 

 different, being entire in the present species and obliquely cruciate in 

 the next, separating at maturity into four sporules. 



EXPLANATION OF PLATE CLVIL 



Pigs. 1. — Taenia atomaria, natural size, 

 2. — Portion of frond with sorus. 

 3. — Same, more magnified. 

 4. — Cells of the surface. 

 5. — Spores from sorus. All magnified. 



