Dr. G. C. Wallich on Desmidiacea from Lower Bengal. 273 



floribus 46, fasciculatis, foliis intermixtis, pedunculo pubes- 

 cente, erecto, calyce puberulo, limbo 4-fido, staminibus 4, 

 erectis, laciniis dimidio brevioribus. Nova Zelandia. v. s. in 

 herb. Hook., east coast and interior (Colenso) ; Foxhill (Dr. 

 Monro) : in herb. Mus. Paris, Akaroa (Raoul) . 



This plant approaches the nearest to Ventenat's typical spe- 

 cies, owing to its very divergent, long and stout spines, and the 

 smallness and paucity of its leaves, in which respects they both 

 assume more of the habit of a Colletia. The branchlets are 

 quite straight, its opposite and almost horizontally-spreading 

 spines are J to 1 inch long ; four or more small leaves, and often 

 as many flowers, are almost fasciculated upon a prominent squa- 

 mose gemma that issues from below the base of each spine : the 

 leaves are 4 or 6 lines long, 1-J line broad, on an extremely short 

 and delicate petiole; the peduncle, the tube of the calyx, and 

 the reflected lobes of its border are each 1 line long*. 



[To be continued.] 



XXXI. Descriptions of Desmidiacea from Lower Bengal. 

 By G. C. WALLICH, M.D., F.L.S. 



[With two Plates.] 

 [Continued from p. 197-] 



BEFORE passing from the filamentous to the non-filamentous 

 genera, I would take the opportunity of pointing out that, how- 

 ever correctly the Desmidiacese may be separated into two great 

 divisions, based upon the presence or absence of the filamentous 

 character, the occurrence of that character in isolated species 

 ought no longer to be admitted for purposes of generic separa- 

 tion. In confirmation of this view, I may mention having ob- 

 served two examples of filamentous aggregation, occurring in 

 isolated species belonging to genera as distinct from each other 

 as it is possible for two genera to be, and occupying positions 

 at the extremes of the non-filamentous division. I allude to 

 Micrasterias and Docidium. In the first of these we certainly 

 should not expect to meet with such a condition. It is never- 

 theless the normal state of a species which shall immediately 

 be described. In the second, on the other hand, we might look 

 for a tendency to assume the filamentous state, inasmuch as the 

 true position of the genus is next to that of the typical filamen- 

 tous genera, such as Hyalotheca. Nothing, I venture to say, 



* A figure of this species will be shown in Plate 37 F of the { Contribu- 

 tions.' 



