AN AQUATIC MYXOMYCETE. 85 



discarded. Under the second group (Endosporece) it is not difficult to 

 refer our species to the Endotrichece, characterised by possessing a 

 capillitium which traverses the lumen of the sporangium, and consists 

 of solid fibres (" stereonemata"). Here we are limited to two of 

 Rostafinski's " tribes " — the Ccdcariacece and the Amaurochcetacece, and 

 a comparison of their characters at once places the present form among 

 the Ccdcariacece. Of the three " families" into which Zopf distributes 

 these genera, the second (Didymiacece) seems to embrace the characters 

 of our form, and it seems very likely to belong to the genus Diderma, 

 having several of the characters of that genus well marked. It is, 

 indeed, not improbable that we have here an aquatic form of D. diforme, 

 one of the commonest of our Myxomycetes, and if so, we have another 

 proof of the all but uselessness of attempting to classify the lower 

 organisms, until we know more of their habits under varying con- 

 ditions. In any case, some of the facts here described show that 

 characters for the description of "genera" and "species" of Myxo- 

 mycetes should be chosen very carefully. 



