80 CORALLINACE^. 



Order III. CORALLINACE^. 



Coralllnece, Lamour. Cor. Class, p. 244. Dne. Class, p. 63. Endl. 3d. Sujypl. p. 

 48. Harv. J^er. Austr. p. 92. Lindl. Veg. King. p.25. Corallinece and Spongitece, 

 Kiitz. Phyc. Gen. pp. 387, 38.5. Kiitz. Sp. Alg. pp. 695, 699- Corallinidoe and Nulli- 

 poridw, Johnst. Brit. Lith. p. 205. 



Diagnosis. Rigid, stony, articulated or crustaceous, mostly calcareous sea- weeds, 

 purple when recent, fading, on exposure, to milk-white, composed of closely packed 

 elongated cells or filaments, in which carbonate of lime is deposited in an organized 

 form. Spore-threads short, tufted in the base of encysted conceptacles, furnished 

 Avith a terminal pore, simple, each thread at length separating into four spores. 



Natural Character. Itoot.^ when manifested, an expanded, crustaceous disc, 

 often spreading widely over the rock or shell to which it is attached. Frond calca- 

 reous, effervescing strongly when thrown into acid, the cells of which it is composed 

 secreting carbonate of lime in an organized form within their walls, and calcareous 

 matter being also deposited on the surface of the cells and between their interstices- 

 The whole compound frond then appears to the eye as if coated with enamel, and 

 when broken, seems equally stony within. On maceration in acid, the I'igid sub- 

 stance becomes soft and pliable, and sub-transparent, and the cellular tissue is 

 obtained free from lime. The cells composing the axis or medullary part of the 

 stem are long, slender and vertical, either closely packed together and overlapping 

 at the ends, or disposed in filamentous series. Those which immediately surround 

 this central layer are shorter and curved outwards, and the cells of the periphery 

 are very minute. A longitudinal section of the stem has frequently a transversely 

 banded appearance, from the cells of which it is composed being nearly of equal 

 length and so placed that their ends stand on a level. 



In outward habit there is considerable variety among these plants. The lowest 

 forms of the order are simply incrustations, spreading like the least organized 

 of the crustaceous lichens, over the surface on which they grow, and like 

 them usually extending from a central point in successive concentric circles of 

 growth. Some are mere films, as thin as tissue paper ; others are thick and 

 stone-like, the crust rising into prominences or sinking in depressions. The sur- 

 face of the thicker crusts is very frequently papillated with conical wart-hke 

 prominences, scattered or densely aggregated. In the more advanced kinds these 

 lengthen into cylindrical processes, and become branched, the bi-anches often so 

 densely crowded that little more than their ends are visible, in which case the 



