ACHLYA in 



TIio six'cios is \"ory near .1. spiiiosa dcHary, and Fischer considers 

 it as the same, l)oth being characterized by very few sporangia (Archer 

 found none). Ho\ve\-cr, as that species has antheridia on about half the 

 oogonia it would seem uniustiruil)Ie at present not to separate them. 

 Humphrey regards .1. coniiita as nearest A. stellata deBary, which he 

 says is almost too similar. The latter has no antheridia, thus agreeing with 

 A. contuta in this respect. As there seem to be no differences of any 

 consequence between the last two species we are treating them as probably 

 the same. 



6. Achlya americana Humphrey. Trans. Amer. Phil. Soc. 17: ii6, pi. 

 14, figs. 7, 9, 10; pi. 15, figs. 24, 25, 29; pi. 16, figs. 30-36; pi. 18, 

 figs. 69-73. 1892 [1893]. 



Plates 33 and 34 



Growth not dense, consisting of stout hyphae with more slender 

 ones intermingled, the largest up to ioo;i. thick at base, the tips pointed. 

 Sporangia long, slender, usually more or less fusiform (one of about 

 average size measured 22 x 370^1.) ; emptying normally, the spores fur- 

 nished with cilia as they emerge (Humphrey), 10.51,1. thick. Gemmae 

 very few, not peculiar, elongated and formed by segmenting hyphae, 

 single or two or three in a row. Oogonia numerous, racemosely f^orne 

 from the base to the tip of main hyphae on short stalks which are usually 

 straight and much shorter than the diameter of the oogonia (rarely 

 oogonial stalks may be several times longer than diameter of oogonia) ; 

 not rarely apical on main threads (fig. 2), no intercalary ones seen (rarely 

 intercalary, Humphrey); spherical, rarely distorted, 40-90;j., most about 

 50-6o;j. thick; walls hyaline, rather thin, pits numerous and obvious. Eggs 

 varying little in size, 18.5-25(1, the great majority about 22;x thick, rarely 

 a very small one about half size occurs with the normal ones, 3-30 or even 

 more, usually 6-12, in an oogonium, eccentric. Antheridial branches an- 

 drogynous, occasionally one from an adjoining strand, one or two, seldom 

 more on each oogonium; arising from the main hyphae near the oogonia 

 or rarely from the oogonial stalk. Antheridia elongated and closely 

 applied to the oogonia, antheridial tubes developed and clearly visible. 



Our cultures were obtained from two sources in vials of water with 

 a little trash kindly sent us in June, 1920, from Woods Hole, Mass., 

 by Mr. George M. Gray, Curator of the Marine Biological Laboratory. 

 In one of these collections there were a good many oogonial stalks that 

 were as long as or even longer than the oogonial diameter, though such 

 were greatly in the minority; in the other strain only a very few, per- 

 haps one or two in a culture, were of such length. It is strange that 

 the species has ne\'er ajijieared in any of our North Carolina collections. 

 Humphrey reports it from Massachusetts, Pennsylvania, .Alabama, and 

 Louisiana, and he speaks of it as "our most abundant nunil)er of this 

 genus, and indeed of this family" so far as he has observed. The only 



