24 THE NORTH AMERICAN SLIME-MOULDS 



Sporangia undefined, obscurely woven in and out among each 

 other forming usually a cushion-shaped asthalioid mass. The outer 

 layer sterile, often calcareous, forming a fragile crust, more or less 

 defined. The middle layer sporiferous with calcigerous capillitium. 

 The lowest layer a membranous hypothallus. 



The identity of this genus seems to have been recognized first by 

 Haller, op. cit., but by Persoon more closely defined and illustrated. 

 Link simply translated the name into Greek, for reasons less evident 

 now, and in this was followed by Fries. Haller's designation is now 

 probably securely fixed. 



The sporigerous median structure of the fructifications, under 

 whatever specific name or names, is entirely confused. Sporangial 

 walls, if ever such there were, are hardly as such recoverable, seem- 

 ingly indicated only, in the changes to which the aethalium submits as 

 in the ripening the sporogenic plasm passes on to spores. 



In the present state of our knowledge the forms of this genus 

 present withal a most perplexing problem. Are they simply phases 

 of a single species, or are they in style and in structure sufficiently 

 constant in their admitted variety, to claim specific rank and separate 

 description ? 



To follow the example of Greville and recognize in all the liter- 

 ature of two hundred years varied descriptions of a single type, — 

 this were perhaps the easier and speedier disposal of the case. Fries 

 thought so to treat the problem but was unable to keep faith with his 

 own decision; for no sooner he states the genus monotypic than he 

 proceeds forthwith to offer four varieties, a. b. c. d., viz. those by 

 Persoon and others duly recognized as species. 



Recent students all, however, seem to find convenience in specific 

 division. All seem disposed to honor Dr. Peck's Fuligo ochracea 

 whether or not by the name he gave; and of other varieties some 

 seem impressed by the constancy of one, some of another character- 

 istic, thus indicating that to careful observers all over the world 

 there are differences that may be recognized, that have been recog- 

 nized again and again. If there are two species there are certainly 

 more. Out of the gatherings of many years one may set in order not 

 less than five variations in the fruiting of Fuligo, five distinct types 





