Geogk. Distr. New Holland. Tasmania. New Zealand. 



Descr. Root brandling. Frond 1-2 feet long or more, decompound-pinnate, 

 1-2-3 lines in diameter, thin, either wholly nerveless or with a very slender 

 midrib; each principal branch narrowed to the base, virgate, 6-12 inches 

 long, bi-tripinnate, lanceolate in outline, the middle pinnae being the long- 

 est, the lower and upper gradually shorter towai-ds base and apex. All 

 the divisions of the frond are geminate, in alternate superposed pairs, the 

 lower of each pair being simple and toothlike, the upper a pinnated or bi- 

 pinnated branch or branchlet. The ultimate lacinia3 are from a broad base 

 subulate, either quite entire or more or less denticulate along the outer 

 edge. In a not unfrequent abnormal condition, some or all of the pinnules 

 towards the base of the branches are excessively divided dichotomously, 

 their divisions capillary and interwoven, each pinnule resembling a little 

 nest of branchlets. Conceptacles 1-2 together, axillary, stalked. SticJddia 

 in dense axillary tufts, half moon-shaped. Colour a bright pinky-red. Sub- 

 stance soft and membranous. In drying it adheres more or less firmly to 

 paper. 



I venture, not without an attentive examination of a very 

 large suite of specimens, to unite under one specific name the 

 Plocamium procerum, J. Ag., and the F. Mertensii, Grev., forms 

 which differ in no other respect save in the ultimate raniuU or 

 pinnules. In the typical P. jiroceriim these pinnules are quite 

 entire, while in P. Mertensii they are finely toothed along the 

 outer edge. Were this character constant, it might be sufficient, 

 but it is far from being so. I find, on the contrary, that the 

 little teeth are sometimes well marked and sometimes very 

 faintly ; and specimens, as might be expected, are not wanting, 

 in which some of the pinnules are quite entire, and some denti- 

 culate, on the same or on diff'erent branches. 



A variety commonly occurs, noticed in our detailed descrip- 

 tion, with dichotomo-multifid pinnules, sometimes general, and 

 sometimes confined to the middle region of the specimen. This 

 form probably grew in w^ater deeper than that usually occupied 

 by the species, as it is analogous to distortions which, in other 

 Algae, I have found prevalent among specimens from deep water. 



Fig. 1. Branch of Plocamium procerum, var. a,' — the natural size. 2. 

 Fragment of P. procerum, var. /8 Mertensii, showing the toothed margin of the 

 lacinules. 3. Fragment of var. a, with conceptacles. 4. Section of a concep- 

 tacle. 5. Spore-strings. 6. Fragment of var. a, with stichidia. 7. Two of 

 the stichidia. 8. K. tetraspore : — more or less magnified. 



