ALGJE. 8 1 



of botany, we find that the latest work, in the form of 

 a " Sylloge," gives the total of Diatomaceae alone at 

 3272 species, with no less than 1 1 18 Desmidiacea; and 

 i860 for the residue of the Confervacea^ ; but even this 

 is not complete, for one section of the Diatomaceae is 

 not yet published. Then v/c have to estimate the 

 Florideae, or red Algae, so well known, by means of a 

 few individuals, to the ordinary visitor to the seaside, 

 as well as the dusky olive sea-weeds, or Fucaceae, some 

 of which attain extraordinary dimensions, and we 

 cannot estimate less than a total of some ten thousand 

 species. 



With the exception of the fungi, the Algns seem 

 to be the most numerous in species of cryptogamic 

 plants, although apparently not more than one-fourth 

 of the number of fungi. The study of Diatomaceae 

 is often pursued by itself, and one great facility lies 

 in the indestructible nature of their flinty valves, or 

 skeletons. After being buried for centuries, enough 

 still remains for their identification, and some of the 

 most beautiful species are those dissolved out of the 

 solid rock. It would be difficult to enumerate all 

 the places where they are to be found, not only in salt 

 water and fresh, but in all places v/here water has 

 ever flowed, and even amongst the excrements of sea- 

 birds. Possibly they are not absent entirely from any 

 tract of country in the world, where there is or has 

 been water. Of almost equal beauty are the Des- 

 midiaceae, but, as these are destitute of any flinty 

 skeleton, they soon perish entirely, so that no trace of 

 them can be found except in the living state ; more- 

 over, for the most part the)' are confined to fresh or 



G 



