674 



SCIENCE. 



[N. S. Vol. XXI. No. 539- 



comparable with that ordinarily secured in 

 ■wye leveling, which is of a much lower order 

 of accuracy. John F. Hayford. 



BOTANICAL NOTES. 



RECENT CLASSIFICATIONS OF THE GREEN ALGAE. 



The appearance of the fourth edition of 

 Engler's ' Syllabus der Pflanzenf amilien ' 

 (whose preface is dated May, 1904, although 

 so far as the green algae are concerned this 

 edition does not difPer from the third, dated 

 July, 1902); Blackman and Tansley's 'Be- 



Charales). Engler sets off the Zygophyceae, 

 Chlorophyceae and Charales as ' branches 

 (Abteilungen) coordinate with Archegoniates 

 (Embryophyta Asiphonogama), and Sperma- 

 tophytes (Embryophjta Siphonogama). These- 

 he subdivides into classes, and the latter di- 

 rectly into families. Thus the class Bacil- 

 lariales contains the single family Bacillari- 

 aceae, including all the Diatoms. West di- 

 vides Bacillariaceae (as a class) into two 

 orders, and these into no less than fifteen 

 families. Blackman and Tansley group the 



Table Showing Outwnes of Classifications of Green Algae. 



I. (Engler). 



II. (Blackman & Tansley). 



III. (West) * 



IV. (Oltmanns). 



Branch Zygophyceae. 



Class Bacillariales. 



Class Conjugatae. 

 Branch Chlorophyceae. 



Class Protoeoccales. 



Class Confe.rvales. 



Class Siphmmles. 

 Branch Charales. 



Class? Characeae. 



Class Isokonlae. 



Series Protoeoccales. 



Series Siphonales. 



Series Ulvales. 



Series Ulotrichales. 

 Class Stephanokontae. 

 Class Akontae. 



Series Desmidiales. 



Series Zygnemales. 

 Class Heterokontae. 



Series Chloromonadales. 



Series Confervales. 



Series Vaucheriales. 



Class Bacillariacae. 



Order Centricae. 



Order Pennatae. 

 Class Heterokontae. 



Order Confervales. 

 Class Chlorophyceae. 



Order Protococcoideae. 



Order Conjugatae. 



Order Siphoneae. 



Order Cladophorales. 



Order Microsporales. 



Order Schizogoniales. 



Order Ulvales. 



Order Chaetophorales. 



Order Oedogoniales. 



(Class) Heterocontae. 

 (Class) Acontae. 



(Order) Conjugatae. 



(Order) Bacillariaceae. 

 (Class) Chlorophyceae. 



(Order) Volvocales. 



(Order) Protoeoccales. 



(Order) Ulotrichales. 



(Order) Siphonocladiales 



(Order) Siphonales. 



(Order?) Charales. 



* The sequence is reversed here so as to facilitate comparison with the other systems. West begins withv 

 higher forms and proceeds from these to lower forms. 



vision of the Classification of the Green 

 Algae' (1903); West's 'Treatise on the Brit- 

 ish Freshwater Algae' (April, 1904), and 

 Oltmanns's ' Morphologie und Biologie der 

 Algen ' (July, 1904) enables us to bring to- 

 gether in parallel columns the different sys- 

 tems of classification which they employ (see 

 table). It will be seen that there is little 

 agreement as to the taxonomic grade of the 

 groups. There is even less agreement as to 

 subdivision of groups, and least of all as to 

 their arrangement. 



In comparing these four systems it must 

 not be forgotten that Engler's and Oltmanns's 

 are general, including all algae, while that of 

 Blackman and Tansley's includes the green 

 algae only (excluding the Diatoms and Char- 

 ales), and West's is confined to British fresh- 

 water algae (including the Diatoms, but not 



green algae into four classes upon a single 

 character, namely, the cilia on the zoospores 

 and gametes, resulting in four parallel lines 

 (classes). Their 'series' are equivalent to 

 ' orders ' in other systems. In West's system 

 the old group Chlorophyceae is nearly the 

 same as Engler's, but with the addition of the 

 Conjugatae. Oltmanns's system, as far as it 

 can be made out from the first volume 

 (' Spezieller Teil'), is much like West's, and 

 includes three larger groups (classes?), the- 

 second and third divided into lower groups 

 (orders?) which in turn are divided into fam- 

 ilies. Oltmanns does not use the terms 

 ' class ' and ' order ' in the volume at hand, 

 and for this reason brackets are used in the 

 table. 



The class Stephanokontae of Blackman and 

 Tansley includes the single family Oedogoni- 



