ALGJE OE SEA-WEEDS. 159 



or lying in fragments along the shore. The first two of these are 

 so much alike, that they may be mistaken for each other, but 

 upon examination it will be found that, although both of the 

 fronds are similar in colour, and pectinato-pinnate, yet Ptilota of 

 the natural family Ceramiaceae has the fructification involucrate, 

 terminating short branches ; whilst Pliacelocarpus has the fruit 

 of both kinds external, and generally pedicellate, and hence Dr. 

 Harvey refers it to the natural family Spha3rococcoidere. Ploca- 

 tnium coccineuni is a cosmopolitan, and, according to Dr. Greville, 

 is " one of the most charming and symmetrical algae in the world, 

 extremely common, and a universal favourite." This species may 

 be often collected at Manly ; but P. confervaceum and P. Pres- 

 sianuvi are not so common. For a beautiful specimen of the 

 latter, I am indebted to Mrs, S. Pearson, of Illawarra, a lady 

 who has devoted much attention to the collection of Alga3, and 

 who, in addition to the species of Plocamium, has succeeded in 

 finding some rare and elegant plants. The species ofl Ceramium 

 which I have found are very small ; but one of them, when mag- 

 nified, is exceedingly interesting, and similar to C. miniatum. 

 Nearly allied to this genus is that of Ballia, of which I have 

 received a specimen from Dr. Mueller, which I believe he pro- 

 cured at the Port Phillip Heads, by dredging. To the same kind 

 friend, I am indebted for . Gelidium r/lanchilcefolium, but this is 

 not a favourite with collectors in general, as it does not adhere 

 to paper. Rhabdonia, Hymenocladia, Rliodymenia, and Nitopliyl- 

 lum occur in different parts of the coast ; but Laurencia seems 

 much more common, and is represented by three species. And 

 yet I have not found any specimen of this genus, so elegant as 

 L. eoncinna, which was collected many years since in New Zea- 

 land, by Mrs. Josiah Betts, when visiting the Bay of Islands in 

 company with her venerable father, the Rev. Samuel Marsden. 

 Thysanocladia laxa has been found by Mrs. Pearson at Illawarra. 

 This, Dr. Harvey mentions " as a rare species, and, like all the 

 others, a deep water plant." The corallines, such as Corallina 

 officinalis, Jania rulens, and Melobesia are very common. These* 

 were formerly regarded by many naturalists as animals, but Dr. 

 Harvey says, " The question of the vegetable nature of corallines 

 may now be considered as finally set at rest by the researches of 

 Kutzing, Philippi, and Decaisne. Whoever macerates a portion 



