154 A CONTBIBUTlOtf TO, ETC. 



paper then, with the specimen properly displayed upon it, is 

 cautiously brought to the surface of the water, and gently and 

 carefully drawn out, so as not to disarrange the branches of the 

 specimen. A forceps, a porcupine's quill, or a knitting needle, 

 or any fine pointed instrument, will assist the operator in dis- 

 playing the branches, and keeping them apart while the plant is 

 being lifted from the water. . . . The specimen, as now dis- 

 played on a piece of wet white paper, is to be placed on a sheet 

 of soaking-paper, and other specimens placed beside it, till the 

 . sheet be covered. A piece of thin calico or muslin, as large as 

 the sheet of soaking-paper is then spread over the wet specimens. 

 More soaking-paper, and another layer of specimens covered with 

 a cotton rag, are laid over the first ; and thus a pile of alternate 

 soaking-paper, specimens, and rags is gradually raised. This pile 

 or bundle is then placed between a pair of flat boards, a weight 

 put on it, and it is left for some hours. It must then be exam- 

 ined, the wet soaking papers removed, and dry ones substituted ; 

 but the cotton rags may be allowed to adhere to the face of the 

 specimens until the latter are perfectly dry, and when they will 

 come off without trouble, even from the most gelatinous kinds." 



The classification of algae is a matter of difficulty, and depends 

 principally upon the different modes of fructification noticed in 

 different parts. Some species which closely resemble each other 

 in appearance, and which by the casual observer would be referred 

 to the same genus, are found to differ greatly in their fructifica- 

 tion, when viewed under a powerful microscope, and hence they 

 must be placed in very different genera. This, indeed, is the case 

 with two of our most admired red sea-weeds, Ptilota and Phacelo- 

 carpus. They may easily be mistaken for each other, so similar 

 are they in the ramification and colour, and in the elegant pecti- 

 nated appearance, of their ramuli, and yet according to a systematic 

 arrangement, they must be placed in families widely separated. 



In order that we may have some general ideas of classification, 

 it is necessary to observe that Phycologists now divide sea-weeds 

 into three sub-classes, viz : (1.) Melanospermece, (2.) Rliodos- 

 permece, and (3.) Chlorospermece, and that these are again sub- 

 divided into families or orders according to their fructification, 

 texture, &c. One of the latest writers on sea- weeds (Dr. Harvey) , 

 makes the following divisions the basis of his system : 



