334 Fresh-water Algae, of Canada. 



" History," that " so abundant are the productions under our 

 consideration, that there is not a ditch or pool of any extent or 

 standing but furnishes one or more species, and even our mineral 

 springs are not entirely free from them. From the uniform na- 

 ture of the element which the majority of the Fresh-Water Algae 

 inhabit, it may confidently be anticipated that very many of the 

 species described in this work, will, when the Algce comes to be 

 studied with that diligence and care they so well merit, be found 

 in most of the Continental countries." In this statement he 

 has exclusive reference to Europe, but he might have extended 

 his view also to America. It is a singular fact, that, while in the 

 Phoenogamus plants, and the higher order of Cryptogams, much 

 that is novel, both in genera and species, may be found in this 

 New World ; yet that the waters, so far as they have been ex- 

 amine,!, present no new forms of Algae, no new genera, and but 

 few plants that are specifically different from those already de- 

 scribed as inhabitants of Europe. It may be found that we have 

 even fewer forms here that are to be found in the more temperate 

 zones of the earth. The severity of our winter, for five months 

 in the year at least, for the most part hinders and may altogether 

 prevent the growth of such delicate plants. Again, our arid 

 midsummer, drying up ponds and streams in which Algae are gene- 

 rally found, is also a hindrance to their developement. On the 

 other hand, the warmth and moisture of our springs and autumns, 

 and the high temperature of our rivers and lakes, are likely to 

 make the genera which we do possess more exuberant and proli- 

 fic. As instances in point, we have not yet found a single exam- 

 ple of the verticellate genus Batrachospermum. In vain we 

 have searched for it in places where it might naturally be ex- 

 pected, yet not a frond have we seen. It may still be found, but 

 so far the researches of two years in the Canadas have been in 

 vain. In contrast with this, we find the allied family, Choetophora, 

 called by Vaucher Batrachosperme a Mamelons, very plentiful and 

 much more prolific in its fronds than as would appear from the 

 descriptions and figures of Hasgall, pertains to the European spe- 

 cimens. This difference between the two hemispheres, future dis- 

 coveries in both will doubtless greatly modify, if not altogether 

 remove. We may, therefore, regard it as an ascertained fact that 

 the Fresh- Water Algce of the old and new worlds are all but uni- 

 form in the number and character of their genera and species. 

 In this paper, we shall follow the classification and generally 



