V. LAURENCIACE^. 67 



structure peculiar to Dasya. The frond is probably several inches long, with an 

 ovate outline, twice or thrice pinnate ; the pinnae elongate, and pinnules short. 

 Both pinnaj and pinnules are closely bordered with distichous, opposite, articulate, 

 confervoid ramelli. Colour a clear carmine. 



Order II.-LAURENCIACE^E. 



HmT. Man. Br. Alg. Ed. 2, jo. 95. Laurenciece, Hook.fil. and Harv. Land. Joum. 

 vol. IV. p. 539. Chondriece in fart J. Ag. Alg. Medit. p. 67. Har-v. Ner. Austr. j}. 

 75. ./. Ag. Sp. Alg. vol. 2, Syn. p. x. Lomentariew, Endl. ^d Suppl. p. 42. Mont. 

 Pol. Sud. Crypt, p. 122. Part of Chondriece, ChondrosiphecB and Champiece, Kiitz. 

 Phyc. Gen. pp. 435, 438, 439. Part of Chondriece, Chanipiece and Polysiphoniece, 

 Kiitz. Sp. Alg. pp. 849, 861, 842. Lomentarieas {partly), Lindl. Veg. Kingd. p. 25. 



Diagnosis. Rose-red or purple seaweeds with a terete or compressed, rarely 

 flattened, inarticulate or constricted and chambered branching frond composed of 

 polygonal cellules. Spor'ferous-nucleus contained in external, ovate or globose con- 

 ceptacles ; spores pearshaped or obconical, subsessile or formed in the terminal cells 

 of unbranched or paniculate, tufted spore-threads. Tetraspores immersed in the 

 branches and ramuli of the frond, scattered without order among the surface cells. 



Natural Character. Boot either a simple disc, or a mat of branching fibres. 

 Frond mostly terete, rarely compressed, more rarely flattened, mostly destitute 

 of midrib, preserving nearly the same breadth throughout, decompoundly branched ; 

 the branches generally repeatedly pinnated, opposite or alternate, rarely whorled 

 or tufted; sometimes, but very rarely, dichotomous. In the first suborder the 

 frond is solid, inarticulate and opaque, of a firmly cartilaginous substance, AvhoUy 

 composed of polygonal cells packed together round a central cell into a honey- 

 combed structure, the innermost cells being largest, those towards the surface 

 gradually smaller, and the superficial very minute. Sometimes tlie axial cells form 

 an articulated single-tubed axis ; and sometimes several longitudinal filaments run 

 through the centre of the stem, like an immersed rib. In the second suborder the 

 branches at least are hollow, constricted at intervals, and furnished at the con- 

 strictions with transverse diaphragms which divide the cavity into separate cham- 

 bers, filled Avith a wateiy mucus, through which a few confervoid filaments, con- 

 necting the diaphragms are dispersed. 



The eoriceptades are of two forms, either globose and destitute of pore, bursting 

 open at maturity ; or ovate, furnished with a terminal pore through which the ripe 

 spores are discharged. These conceptacles are either formed in the hollowed apex 



K 2 



