256 ARCHER, ON MICRASTERIAS MAHABULESHWARENSIS. 
scription, in a puzzling and contradictory manner, calls “ the 
surface of the frond covered with small granules bordering 
the whole of the sinuses,” so that we are obliged to rely al- 
most wholly on his figure; but of the identity of these two 
plants there can, I think, be no doubt. 
It is to be regretted that Dr. Wallich in his paper has 
spoken of the species referred to as M/. morsa (Ralfs), whereas, 
the name M. Americana (Ehr.) having the priority, it should 
have the precedence. It will therefore be understood, that 
when I refer to M. Americana, it is equivalent to M. morsa 
as alluded to by Dr. Wallich, and I mean by the former name 
precisely the same identical plant. Dr. Wallich, indeed, him- 
self draws attention to this in a note. 
This presumed form, then, of M. Americana (EKhr.), which 
I can do nothing else than assume as identical with M. Maha- 
buleshwarensis (Hobs.), Dr. Wallich makes var. 6 of that 
species of which he considers M/. Americana the type, and 
along with it he would include both M. Baileyi (Ralfs), and 
M. ringens (Bailey)—the two latter indeed, forming but a 
single variety of the assumed species M. Americana. But in 
this conclusion I feel bound to say, with much deference, 
that I cannot at all concur. Dr. Wallich, indeed, seems to 
overlook, and I regard the consideration as very worthy of 
attention, that Professor Bailey, who had seen the living forms, 
has, in his published list,* enumerated the whole three, that 
is, M. Americana, M. Baileyi, and M. ringens, as so many 
distinct species. I admit, indeed, that the short technical 
characters given by Dr. Wallich would almost, if not quite 
as well, apply to the actual M. Americana (Ehr.); but, paying 
attention rather to his subsequent general description, and to 
his, I have no doubt, very graphic figure, and comparing 
them with Ralfs’ figures,t+ or, even better still, with an actual 
specimen, surely, I think, abundant differences will present 
themselves to any one who examines them. Dr. Wallich 
himself, indeed, in describing his form more at large, points 
out briefly its distinctive marks; but then he considers these 
as only of importance sufficient to induce him to regard the 
form in question as a variety of M. Americana. 
But I must urge that if, in distinguishing species in this 
family, differences—tangible, readily describable, constant 
(at least in British species, even if often less striking, I be- 
lieve them, on the whole, to be constant) characteristic dif- 
ferences are to be lost sight of and ignored, and only resem- 
* «Smithsonian Contributions to Knowledge,’ ‘ Mic. Obs. made in 8. 
Carolina, Georgia, and Florida,” p. 29. 
7 ‘British Desmidiee,’ p. 74, t. x, 1. 
