66 
I desire to place on record that I have seen at least two 
apparently and generally acknowledged free species of Des- 
midiaceae attached to a submerged aquatic moss. One 
was, Closterium, species not determined, which was for a long 
time (as during the most of last summer the specimens were 
growing in one of my aquaria) attached pretty firmly, by 
means of a true stipes or stalk of no great length, to the 
leaves of the moss, and that so strongly that it required some 
considerable force to detach it. By rocking the covering 
glass upon the slide, upon which the specimen of moss was 
placed during observation by means of the microscope, the 
Closterium could be made to swing about from side to side 
upon its stipes without becoming detached. The other 
species, observed at the same time, was a Micrasterias, and 
this was fixed, generally in pairs, to the same moss, by its 
broadest side, or by both valves, so as to present a “ front 
view” (as it is termed when speaking of Diatomaceae) to 
the observer, thus presenting an analogy to the genus Epi- 
themia of that family which occurs growing after the same 
manner ; Cocconeis, on the contrary, is attached by means of 
the whole of one of the valves. The stipes of the Closterium 
was, of course, at the end of the frustule where the valve 
comes to a point, after the manner of a Cocconema, which 
genus Closterium resembles much in form. In neither of 
these cases do I designate the species, as that I deem hardly 
of importance, the mere fact of Desmidiaceae being found 
under such conditions being the important one. At the 
same time it is as well to mention that these species were 
thus found during the month of August, or in the midst of 
the summer, the same forms having been observed free and 
movable in the early part of the spring. 
I have now to place upon record my opinion that the 
Desmidiaceae are governed by very much the same law as 
applies to their apparently near allies the Diatomaceae ; that 
is to say, that they are all at some period of their existence 
attached, and at another free. 
