BOTANY OF rERNANDO NORONHA. 75 



squamis imbricatis rotundatis ultra marginem paulum exstantibus 

 purpureis margine pallido. 



Hah. loco liiimido umbroso Tangle Eock, Insula Eernando 

 Noronha {R. N. Bidley, Aug. 1887). 



Dimensions of frond, 5x2; spore O'l x 0'6 mm. 



This sj)ecies falls into the scale-bearing section of Bischoff's 

 subgenus Lichenoides. It most resembles R. limbafa, Bisclioff, 

 but differs in the less acute, non-ascending margin of the thallus, 

 the colourless border of the scales, and tbe direction, which is at 

 right angles to the margin of the thallus. The scales spring 

 from the purple membrane, which covers the underside of the 

 thallus for about one half of the distance from the margin to the 

 median line, and exhibits obscure transverse folds. The scales 

 are exj^anded laterally so as to overlap one another in an imbri- 

 cate manner. The laciniae are emarginate, devoid of papillre, and 

 still united to the withered main thallus ; they bear the fruit 

 beneath the upper surface in the median groove. Several arche- 

 gonia, but only one ripe fruit has been observed. Several 

 minute closely involute thalli occur beneath the older plants. 

 The latter are aggregated together, and are very firmly attached 

 to the soil by innumerable short hairs. 



ALGtM. 



By Geoege M. Mueray, P.L.S. 



The Algse collected by the ' Challenger ' Expedition at Fernando 

 Noronha and recorded by the late Professor Dickie (Linn. Soc. 

 Journ. Bot. vol. xiv. p. 363) have been included for the purpose 

 of completing the enumeration of Algse from this island. 



Ploeide^. 



Centeoceras clavulatum, J. Ag. 



Ridleij, Lea, and Bamage ! 



Geogr. Distr. Throughout tropical and subtropical seas. 



G-iGAETiNA Teed II, Lam. 



Ridley, Lea, and Ramage ! 



Geogr. Listr. Atlantic and Mediterranean. 



Cheysymenia enteeomoepha, Harv. ? 



' Challenger.' 



Geogr. Distr. West Indies. 



