128 BihUographical Notices. 



ley's ' Introduction to Cnpto^amic Botany ' abounds M'itli interest- 

 ing remarks upon various genera, but does not profess to sj-stenia- 

 tize lower than orders. Tlie treatises of Mr. Kalfs and of the late 

 Professor Smith have deservetUy acquired a classical reputation ; 

 but they are only nionograi)hs of special families. There is an 

 immense amount of accurate information scattered through the 

 pages of the ' Micrographic Dictionary,' which, if coUccted, ar- 

 ranged, and somewhat ampliticd, would go a long way towards suj)- 

 plying the deficiency. Dr. (Jray's useful ' Handbook ' is only in- 

 tended as a catalogue to assist in the arrangement of Algie for the 

 herbarium, and does not contain any specific characters. 



It is therefore a great satisfaction to meet with a work which has 

 gathered up the great mass of scattered information relative to the 

 Alga? of Europe which inhabit fresh or brackish Avater ; it affords 

 a soi't of resting-place from Avhich to start afresh for the investiga- 

 tion of the numberless questions which still remain to be deter- 

 mined with regard to the plants now under review. No one would 

 be more ready than Dr. Eabenhorst himself to admit that his work, 

 valuable as it is, is far from exhaustive of the subject. As regards 

 one great tribe, his PliifcocIironiojiJit/cece, he himself remarks that our 

 knowledge is still " valde imperfecta et manca ;'' and indeed it may 

 be a question, as will be seen in the sequel, whether most of the 

 genera of this division may not prove to be wholly inadmissible. 



With these preliminary remarks, we will iirocecd to give some 

 account of the contents of the work before us. 



Dr. Kabenhorst (as is perhai)s unavoidable in treating only of the 

 freshwater Alga?) departs somewhat from the hitherto generally re- 

 ceived classification. Instead of dividing the group into Chloro- 

 sperms, Ehodosperms, and Melanosperms, he constitutes five classes : 

 — 1. DiatomophiicecK (or Diafomacecn) ; 2. PJufcochromophi/cece ; 

 3. ChJorophiiUojilnjcecn; 4. Melunoplujcetv ; and 5. lihodophycea;. Of 

 these, the three latter comprise such of the Alga? of the three (ivd- 

 sions just mentioned as are not removed into the Biatomojihycece and 

 Phjicochromophiicen'. 



AVith regard lo the first class (the Diatomojjhifceif or Dutiomaceit'*), 

 there will probably be few botanists who will object to their having 

 a scj)arate division assigned to them. Their very remarkable struc- 

 ture, their mode of reproduction, their ajijiarent Avant of immediate 

 affinity with any other of the plants known as " Alga?," afford 

 quite sufficient grounds for keeping them by themselves. They seem 

 out of place amongst the C'hlorosperms, to which they have been 

 hitherto referred, and if removed from that division it would be 

 im])Os.sible to do otherwise than to make them a class by themselves. 



Dr. llabenhort-t divides the Diatomuceo' into fourteen families. 



To go at any hmgth into the discussion of these wotdd occupy 



• The term Diatomophycea> has evidently only been adopted to pre- 

 serve a kind of unilonnity of uomenclatm-e with the other four classes ; 

 but it is an awkward expression, and will certainly not be allowed to 

 displace the well-known nanio " I)!(it<i)iKucf^y 



