470 POLYMORPHISM AND LIFE-HISTORY IN THE DESMIDIACEiE, 



hence our forms of Doc. maximum dijBFer in this respect from 

 European cells. This variation is rare here, and the two cells 

 figured are the nearest approach to the shape of maximum that 

 I have ever seen. 



The order of growth in the trahecida-^t&ge of this species is, 

 (1) var. Brefeldii, (2)var. Iruiicatum,, (3) traj)ecula, (4) var. crenu- 

 latum, (5) var. maxitnum — the last occasionally only. 



Var. DIADEMATUM, n.var. (Pl.xi., f.8). 



Forma lateribus parallelis apices versus convergentibus; basi 

 levissime inflata; apicibus granulis validis distinctis ornatis. 

 Long.494-600; lat. bas.37-43; ap.21-24/x. 



Collector; Coogee(l); Prospect(43); Auburn(lO). 



Found with var. Ehrenhergil&nd var. crenulatum. Thisform dis- 

 tinctly shows transition going on from the slenderer forms of var. 

 Ehreiibergii and var. Deljwntei to the stouter ones of trabecula 

 proper, by increase in breadth from the base upwards. The 

 upper part of these semicells belongs to the former, as the apex 

 clearly shows; the lower half to the latter. 



This coroneted ajiex is never found in the trabeculaiovms 

 proper, but is peculiar to the stout form of E]irenhergii[va.r. Del- 

 pontei mihi). Tlie apex, though it looks so strong, is not per- 

 manent; the granules are merely rucks in the membrane, and, as 

 the inflation of the semicell proceeds upwards, it smooths them 

 out, producing the typical crenulatum-a-pex with faint plicie. 



Subspecies Doc. Ehrenhergii mihi. 



I use this expression simply as a subheading to indicate a 

 definite biological group of forms within the species. The word 

 subspecies has formerly been embodied in the name of the Desmid. 

 This is, however, not absolutely necessary, and complicates the 

 nomenclatuie to such an extent as to be quite intolerable. It is 

 absurd that one should have to employ a whole line of print in 

 order to make passing reference to some particular form; and, 

 while it is most important that the various forms should be 

 arranged according to their natural biological connection, yet why 



