SEAWEEDS. 171 



The last family of the Cladospermere, that of the 

 Osyillatorise, is composed of very minute members. They 

 are formed of small jointed threads, each composed of a 

 simple tube. The name Oscillatorise is given to the 

 order because of the constant movement of the fronds. 



The first family in the order is called Rivularia, because 

 many of its members inhabit rivers, of which more anon. 

 We found one of the marine species, the Shining Bivularia 

 (R. nitida, Cut I., fig. 11), on rocks at Arran, which it 

 rendered terribly slippery. It grew upon the flat part 

 of the rocks filling every tiny crevice, and plentifully 

 sprinkling the fronds of the Rock Cladophora. The 

 fronds are round, black green, and glossy, seldom as large 

 as a good sized pea. All the species in this family are 

 more or less globose, the threads composing them being 

 woven together into that form. 



When we came to examine some of the red weeds we 

 had gathered in such abundance at Ardrossan, we found 

 them beset with little tufts of green threads. The simple 

 form of the thread-like fronds, and their veins devoid of 

 motion, pointed out the little parasite as belonging to the 

 Callothix family ; its glaucous hue fixing the species as 

 the Conferva-like (C. confervicolor, Cut I., fig. 12). Other 

 members of this family grow upon rocks near high-water 

 mark, or are parasitic on different algae. 



Lyngbye's sea- weeds are green, with thread shaped 

 fronds marked with rings more or less clearly. They 

 greatly resemble Confervas, and their fronds are disposed 

 in layers upon rocks, mud, sea-weed, or floating timber. 



Thus in a comparatively short season we gathered 

 together a fair number of seaweeds. We had OhVe weeds 



