232 INTUODUCTION TO CRYPTOGAMIC BOTANY. 



by the disposition of the bladders and receptacles, and in the 

 more or less distinct evolution of distinct leaf-like organs. 

 While some assume the most elegant foliage, set off by the 

 bunches of receptacles and the elegant vesicles, others present 

 stiff and rugged stems with prickly processes, which bear little 

 resemblance to leaves, or at least to such as have an expanded 

 lamina. 



222. Splachnidium, a genus almost confined to the southern 

 hemisphere, is in appearance and consistence merely a mag- 

 nified form of the receptacles of our common seaweeds, being 

 equally gelatinous and difficult in certain states to preserve. The 

 frond and receptacles are altogether confluent. D' Urvillcea, 

 one of the most extraordinary of Algse, is allied to Hintian- 

 thalia, with which it agrees in habit, though so much larger 

 in its dimensions. It has no receptacle distinct from the frond. 

 The structure of the frond is extremely beautiful, which is 

 distinguished by very large and regular cavities, so as to 

 resemble a honeycomb. As in the neighbouring genera, the 

 spores are quadrifid ; and it is probable, from Dr. Hooker's 

 observations, that there are antheridia on the same plant. 

 The poorer classes of Western Chih use this plant for food, 

 and the soup made with it is sweet and mucilaginous. The 

 dichotomous fronds, which are two inches or more broad, attain 

 the length of ten feet. Sarcophycus is very nearly allied. 

 The only species, S. potatorum, so named from pieces of the 

 frond being used to hold water, has been proved by Dr. Hooker 

 to have fruit precisely of the same structure as D' Urvillcea. 

 These are succeeded by genera in which there is some Kttle 

 distinction at the base, as Myriodesma and Garpoglossum, 

 all the species of which belong to the southern hemisphere. 

 We have, however, on our own coasts a seaweed of great sin- 

 gularity from the excessive disproportion between the frond 

 and the receptacle. The frond of Himanthalia is a small 

 Pezizseform knob, from a depression in the top of which spring 

 one or two papilla, which ultimately give rise to a dichoto- 

 mous thong-hke receptacle, two or three feet in length, 

 entirely covered with fruit. The true frond sometimes becomes 

 hollow and swells into a bladder. H. lorea extends from 



