24 



CERAMIACEiE. 



[Thallogens. 



in the different species of Griffithsia. We see them enlarge for a certain space of 

 time, and present the appearance of a rose-coloured globule ; but at a more ad- 

 vanced period the external envelope dilates, becomes transparent, and the central 

 body, considerably increased in size, tends to separate into four parts or distinct spores, 

 each invested with a special envelope, and of the most brilliant carmine colour. This 

 structure brings to mind, with some slight differences, that of pollen grains." And 

 then M. Decaisne goes on to explain how, by a stoppage of growth, or by interior mul- 

 tiplication, the quaternary character cf these bodies may be affected. 



According to Endlicher, the maximum of tin's order is found in the ocean between 

 35° and 48" N. lat. They are entirely marine. Towards the pole and the equator they 

 diminish in numbers, and are comparatively rare in the southern hemisphere. Rhodo- 

 dermis Drummondi covers the rocks of caves with patches of a dark blood or brick- 

 red colour. 



It is among the genera of this order that occur the seaweeds whose gelatinous quali- 

 ties render them valuable as food. Many species are so used among Indian nations. 

 Of them Plocaria tenax, and Candida, are the principal ; and the material out of which 

 the swallows construct the esculent nests which are so highly valued by the Chinese, is 

 supposed to be a sort of Gelidium. The British Plocaria compressa, and Chondrus cris- 

 pus (or Carrageen moss),have been found to possess similar qualities ; and another species 

 of the order, on the south-west coast of New Holland, furnishes a jelly of great excel- 

 lence. Rhodomenia palmata, the dulse of the Scots, dillesk of the Irish, and saccharine 

 Fucus of the Icelanders, is consumed in considerable quantities throughout the mari- 

 time countries of the north of Europe, and in the Grecian Archipelago ; Iridsea edulis 

 is still occasionally used, both in Scotland and the south-west of England. Laurencia 

 pinnatifida, distinguished for its pungency, and hence called Pepperdulse, is eaten in 

 Scotland ; and even now, though rarely, the old cry, " Buy dulse and tangle," may be 

 heard in the streets of Edinburgh. 



But it is not to mankind alone that such marine Algals have furnished luxuries, or 

 resources in times of scarcity. Several species are greedily sought after by cattle, 

 especially in the north of Europe. Rhodomenia palmata is so great a favourite with 

 sheep and goats, that Bishop Gunner named it Fucus ovinus. One species is invaluable 

 as a glue and varnish to the Chinese. This is the Plocaria tenax, the Fucus tenax of 

 Turner's Historia Fucorura. Though a small plant, the quantity annually imported at 

 Canton from the provinces of Fokien and Tchekiang is stated by Mr. Turner to be 

 about 27,000 lbs. It is sold at Canton for Gd. or 8d. per pound, and is used for the pur- 

 poses to which we apply glue and gum-arabic. The Chinese employ it chiefly in the 

 manufacture of lanterns, to strengthen or varnish the paper, and sometimes to thicken 

 or give a gloss to silks or gauze. It seems probable that this is the principal ingredient 

 in the celebrated gummy matter called Chin-chon, or Hai-tsai, in China and Japan. 

 Windows made merely of slips of Bamboo, crossed diagonally, have frequently their 

 lozenge-shaped interstices wholly filled with the transparent gluten of the Hai-tsai. 

 On the southern and western coasts of Ireland, our own Chondrus crispus is converted 

 into size, for the use of house-painters. 



In medicine we are not altogether unindebted to Rosetangles. The Plocaria Hel- 

 minthochorton, or Corsican Moss, as it is frequently called, is a native of the Medi- 

 terranean, and had once a considerable reputation as a vermifuge. To Hypnea mus- 

 ciformis similar qualities are ascribed in the Greek Archipelago. Several species 

 furnish Iodine, which gives them an odour of violets. Rytiphlcea tinctoria yields a red 

 dyeing matter, the Fucus of the ancients. The Plocaria Candida, or Fucus amylaceus, 

 has been found to consist of pectine, gum, and starch, with a pretty considerable quan- 

 tity of inorganic matter, especially sulphate of lime. (Ch. Gaz. 1843, 638.) The Tsan- 

 tjan or Kanten (called Fucus cartilaginosns), used in China as a substitute for the 

 edible birds'-nests, seems to have a similar composition. 



GENERA. 



Suborder I. — Ceramea. 



Frond tubular, jointed. 

 Favella: containing a 

 loose mass of semi- 

 transparent granules 

 in a gelatinous enve- 

 lope. Tetraspores ex- 

 ternal. 



CaUithamnion, Lyvgb, 

 Ballia, Harvey. 

 Griffithsia, Agh. 



Plumaria,Lk. 



Polyehroma, Bonnem. 

 Wrangelia, .•/.<;/<. 



Spyridia, Ilarv. 

 Binders, J. Agh. 

 Ceramium, Adams. 



Boryna, Gratel. 



JHctyderma, Bonnem. 

 Ptilota, Agh. 



Plumaria, Stackh. 

 Microcladia, Grev. 

 1 Ilaplolegma, MonL 



Suborder II. — Cryptone- 



mece. Frond cellular. 

 Favellidia containing a 

 lirm mass of compact 

 granules within a gela- 



tinous envelope. Tetra- 

 spores globose or ob- 

 long, formed out of 

 cells of the circum- 

 ference. 



«) Gloiocladidae. 

 Crouania, J. Agh. 

 Pudresnaya, Bonnem. 

 Naccaria, Endl. 



Chtetospora. Agh. 



CapUlaria, Stackh. 

 Gloiocladia, J. Agh. 

 Gloiopeltis, J. Agh. 

 Nemalion, Targ. 



Hdminthora, Fries. 



6) Nemastomidse. 

 Catenella, Grev. 

 Endocladia, J. Agh. 

 Iridsa. Bory. 



A'emasloma, J. Agh. 



Dilsea, Stackh. 



c) Spongiocarpidse. 

 Furcellaria, Lainx. 



Fastigiaria, Stackh. 

 Polyides, Agh. 



Spongiocarput, Grev. 

 Bhododermis, Ilarv. 

 Thuretia, Dec. 



