1 6 HANDBOOK OF SEA-WEEDS. 



Wrangeliaceoe. There is only one native species in each, both 

 being rare, the latter especially. 



The Helminthocladioe are also a limited group, of a gelatinous 

 structure ; so much so that on being gathered they feel like a 

 bunch of slimy worms, whence the name of the family. Hel- 

 minthora purpurea and divaricata with Nemaleon multifidum 

 and Scinaia furcellata represent them in Britain. They are 

 nearly all very rare, pretty plants, and very effective as micro- 

 scopic objects. 



The Squamariae, formerly included in the Corallinacese, are a 

 small group of inconspicuous plants resembling lichens, of a 

 leathery texture, and growing on rocks and shells attached by 

 their lower surface. 



A single genus only, Polyides, represents the Spongiocarpeoe. 

 Polyides rotundus resembles Furcellaria fastigiata very closely, 

 but differs widely in the fruit, which consists of spongy warts 

 surrounding the frond, composed of spores and articulated 

 threads. 



Of the next group represented in Britain, Gelidiaceae, we 

 have only one plant, Gelidium corneum, very common on our 

 shores, and perhaps the most variable of all vegetable species. 



The Sphoerococcidse include both membranaceous and cartila- 

 ginous species. Of the latter is Sphcerococcus coronopifolius, 

 which cannot easily be mistaken, owing to the numerous berry- 

 like fruits that tip its branchlets. It is rather rare on the 

 northern, but often thrown ashore in large quantities on the 

 southern coasts. The genus Delesseria has four British species, 

 the largest being the well-known D. sinuosa, the fronds of 

 which resemble an oak leaf in outline. The handsomest are 

 D. ruscifolia and D. hypoglossum, which are more delicate and 

 of a finer colour than sinuosa. There are three British species 

 of Gracillaria, in two of which the branches are cylindrical, and 

 in the other flat. G. compressa makes an excellent preserve 

 and pickle, but unfortunately it is the rarest of the three. 

 Nitophyllum is one of the greatest ornaments of this tribe. 

 There are six British species, which are amongst the most deli- 

 cate and beautiful of our native Algce. 



The Corallinaceoe are remarkable for the property they 

 possess of absorbing carbonate of lime into their tissues, so that 

 they appear as a succession of chalky articulations or incrusta- 

 tions. The most common is Corallina officinalis. There are 

 two British species of Corallina, and two also of the nearly 

 allied genus, Jania. Of the foliaceous group there are likewise 

 two British genera, Melobesia and Hildenbrantia. 



