OP CEYLON AND INDIA. 
271 
In earlier times these plants were commonly mistaken for 
algæ or lichens or even mosses ; the resemblance is so great 
in many cases, especially in the vegetative condition, that 
such mistakes are quite excusable. The resemblance is also 
indicated by the frequency of such specific names as 
bryoides, fucoides, algæformis, lichenoides, &c. The first to 
be described and made the type of a distinct family was 
Mourera fluviatilis, found in 1775 by A.ublet (1) in French 
Guiana. He describes it as growing upon the rocks at a 
great cascade in the Sinemari river, where it is always sub- 
merged, only the floriferous part coming above the water. 
Little progress was made in the knowledge of these plants, 
and comparatively few had been described, until the 
publication in 1849 and 1852 of Tulasne’s monographs 
(38, 39). He divides the order into 21 genera, describing 79 
species, most of them for the first time. The second paper 
is illustrated with beautiful figures, which show in a very 
striking way the great variety of form which exists among 
these plants. Tulasne’s descriptions and detailed analyses 
are very accurate, much more so than those of some of his 
successors. It will be noticed that in the preceding paper I 
have returned almost completely to his definitions of the 
generic and specific forms of the Indian Podostemaceæ. His 
interpretations of the morphology, as is only to be expected 
in a work of that period, are often misleading. 
The systematic part of Tulasne’s work was continued by 
Weddell (46), whose monograph has been the standard for 
subsequent classifications of the order. His work, however, 
at any rate so far as the Indian forms are concerned, is 
inferior to that of Tulasne in accuracy and insight, and he 
does not deal at all with the morphology or ecology, except 
in a separate paper (48), where he treats the order with 
reference to its geographical distribution, and in which he 
calls attention to the limited distribution of the species as 
compared with most water plants, noting especially the 
curious fact that in the rivers which he studied in 
South America the forms were different at each cataract 
