GROWTH, ETC., IN THE DESMIDIACE.E. 297 



(3). Base inflated, sides straight, Subspecies maculatum. 

 var. maculatum (Turn.), I.e. 1892, T. iv, f. 3. Apex inflated. 

 (Syn. D. robustum Turn., T. ii, f. 8) 

 (Syn. D. elatum Turn., T. ii, f. 16) 



(Syn. D. coron. Grun., Josh., Burm., 1886, PL 25, f.16,17) 

 var. W allichianum (Turn.), T. iii, f. 2. Apex half formed. 

 var. cristatum (Turn.), T. iv, f. 7. More slender, apex square. 

 (Syn. D. orientale Turn., T. iv, f. 1) 

 (Syn. PI. moniliferum W. & G. S. West, Alg. Mad., 



1894, PI. V, f. 32) 

 (Syn. D. sub-coronulatum Turn., I.e. T. iii, f. 1) 

 (Syn. D. cylindricum Turn., I.e. T. ii, f. 11) 

 var. detum (W. & G. S. West), N. Amer. Desm., 1895, PI. xiii,. 

 f. 2, 3. 



Subspecies eiigenciim. 

 (4). Rugffi only at apex, within the margin, or not yet formed, 

 var. eugeneum (Turn.), I.e. 1892, T. iii, f. 3. 

 var. gloriosnm (Turn.). I.e. T. iii, f. 5. 

 var. parallelum (W. cS: G. S. West), Alg. Madag., 1894, PI. v, 



f. 34. 

 var. indicum Turn, (non Grun.), T. iv, f. 8. 

 Immediately, however, an attempt is made to work out the 

 life-history of a species it becomes clear that in some genera there 

 are distinct biological subspecies entirely at variance with the usual 

 sciagraphical ones, the latter being merely artificial, while the 

 former are natural. Doc. coronulatum would have furnished an 

 excellent object lesson in these. Unfortunately, though the species 

 occurs here, it is not common enough for me to have made any 

 observations on its life-history. I will therefore endeavour to shovv 

 these biological subspecies in the chart of a common and well- 

 known species — Doc. trabecida — in which, luckily, they are very 

 plainly shown, and whose various forms I have pretty thoroughly 

 investigated. 



Biological chart of the species Doc. trabecula : — 

 Diam. 60-85 u. 

 v. truncatum major =v. nodulosum=-w . coronatum 



v. maximum (Reinsch) 



A 



v. Archerii (Delponte) 



Diam. 40-60 u. j 



v. truncatum minor ^^trabectda^trab. v. cremdatum (R. & B.) 



A 



I . . . 



V. Delpontei miht 



A 



.1 



v. constrictum mihi 



Diam. 10-40 u. ] 



v. baculum=v. baculoides=w. Ehrenbergii=^v. indicum (Grun.). 



