530 THE SEA-WEED FAMILY. 



into a detailed account of them, or of any other portion of the family. 

 It must sufl&ce to say that the Manchester species are almost wholly 

 aquatic, inhabiting ponds, ditches, streams open to the sun, and the 

 bosoms of gloomy fountains, some preferring to live in stagnant water, 

 others in the piircst and clearest. The student who would wish to 

 learn something of them should consult Hassall's " British Fresh-tvater 

 Algcn^^ 2 vols., 8vo, the second consisting of coloured drawings; Smith's 

 " British Diatomacece" and Ralfs' " Desmidiece^^ also very copiously 

 illustrated. The greater part of the Manchester species and localities 

 were originally published in the last-named work. Mr. Notcutt's 

 ^'^ Hand-book of the Microscope and Microscopical Objects," pp. 62 and 

 132, contains some very useful directions how to find and examine 

 these beautiful and inconceivable little plants. 



The three great families of Thallogens, the Lichens, the Fungi, 

 and the Alga;, each take us to the very lowest point of vegetable 

 structure. Perfectly distinct in their larger forms, it is difficult to 

 draw up any positive and absolute differential characters by which 

 they shall at all times be discriminated one from the other ; the easiest 

 and safest, as a general rule, lie perhaps in their habitats and mode of 

 sustenance, and may be tabulated as follows : — 



Growing in water, Algjj. . . ) Nourishment drawn from the medium in which 

 Growing in air, 



Lichens.) •' 



Fungi.. . Nourishment derived from the dead or decaying 

 organic matter on which they are seated. 



LIST OF SPECIES. 

 1. Conpervaceje. 



Vaucheria dichotoma. 



E. B. xiii. 932 (as Conferva dichotoma). 



Dillivynii. 



sessilis. 

 geminata. 



E. B. XXV, 1705. 

 E. B. XXV. 17C6. 



Lemania fluviatilis. 



E. B. XXV. 176!( (as Conferva Jliiviatilis). 



Batrachospermum moniliforme. Abundant in the neighbourhood of 

 Whitworth, near Rochdale. (Mr. Tom Stansfield.) 

 E. B. X. R89 (as Conferva gelatinnm). 



