(120) 



This lovely little " gem of the sea " is rare in this country, and 

 scarcely less so on the shores of Continental Europe, and although no 

 doubt often overlooked on account of its small size, is most likely of 

 scarce occurrence, as it has not been observed in numerous places 

 which have been carefully examined by celebrated collectors. 



In structure, as well as in fructification, it is closely related to Calli- 

 thamnion, the minor character in habit being almost the only one to 

 separate it from that genus, with which some authors unite it. 



Although its small size, and not very brilliant colour, render it by no 

 means a very conspicuous object in a rock-pool, yet when growing para- 

 sitically, and in a mass, its delicate waving fronds form a most beautiful 

 and interesting object ; its dense whorls of ramuli give the fronds a 

 beaded appearance, and render them more susceptible of motion from 

 the slightest movement in the water ; placed under the microscope, 

 the beautifully beaded fronds, the numerous articulations on the little 

 reddish brown globule of endochrome within its hyaline tube, form a 

 very pretty object, and when dotted over with the dark coloured 

 tetraspores, a more lovely object could hardly be conceived. 



EXPLANATION OF PLATE CIX. 



Fig. 1. — Groiiania attenuata, natural size. 

 2. — Branchlet with whorled ramuli. 

 3. — Tetraspore from same. 

 4 . — Ramulus from whorl. All magnified. 



