126 THE SAPEOLEGNIACB^ OF THE UNITED STATES, 



while he has figured several such. It should be, however, readily enough recognized 

 by the usually barrel-shaped oogonia, with numerous blunt, and often broad or even 

 forked, outgrowths, each containing one or two oospores which often take an ellipti- 

 cal form corresponding to that of the cavity of the oogonium. The principal hyphas 

 commonly produce very abundant closely set, short, lateral branches that give to the 

 whole plant a densely woolly appearance ; and reproductive organs are often produced 

 only when these branches reach a new food-supply and give rise to fruiting hyphse. 

 The species was obtained by DeBary from a lake in the Black Forest, known as the 

 "Titisee." 



AcHLYA CORNUTA Archer ('67). 



111. : Archer, '67, PI. VI, Figs. 2-6. 

 PI. XX, Figs. 103, IO4. 



Hyphae of medium size, short. Zoosporangia rare, cylindric. Oogonial branches 

 rarely long, straight or flexuous, racemosely arranged. Oogonia terminal, globular 

 or elliptical, densely beset with rather long, blunt outgrowths of their unpitted walls, 

 the apical one often larger and forming an evident apiculus. Antheridial branches 

 and antheridia wanting. Oospores from one to four in an oogonium, globular or 

 slightly flattened, centric, their average diameter about 29y;i. 



Massachusett s — Amherst. Europe. 



The same culture which yielded A. megasperma for the first time contained a 

 small amount, all I have seen, of this form. It has been referred with some doubt to 

 Archer's species, since it fails to show at all a feature which one would suppose, from 

 that author's account and figures, to be very characteristic of his plant ; namely, the 

 development of several oogonia in a series from a single hypha. In other respects, 

 however, it corresponds too closely with his description to justify one in regarding it 

 as distinct. Archer saw no sporangia, probably not, as he thought, because he found 

 it too late, but because of their rarity. In species which produce sporangia abund- 

 antly, one can always find empty ones on plants with mature oospores. In the limited 

 material at my disposal, I have been able to find but a single one, and that only long 

 after it was emptied. From below its base arose a branch bearing an oogonium. 

 This, so far as it goes, supports Archer's conclusion that the plant is an AcJilya, 

 which seems almost certainly correct. The oogonial branches sometimes show the 

 incurving mentioned by Archer, and are often less definitely bent. This writer states 



