ACIILVA 139 



Achlya radiosa Maurizio. Mitt. d. Deutsch. Fischerei-V'ereins 7, Heft 1 : 



57, tigs. 18 and 19. 1S99. 

 A. decorata Petersen. Bot. Tidsskr. 29: 3S6. 1909. Also in Ann. 



Myc. 8: 522, figs. 3a and 3e. 1910. 

 A. asterophora Mindon. Krypt. FI. Mark B. 5: 549, fig. 2c on p. 



520. 1912. 



This species, described three t'mcs in rather recent \'ears in Europe, 

 has not been found in America. The prior description by Maurizio 

 may be condensed as follows: 



Hyphae dense, about 1-1.5 cm. long, i4.5-49;x thick, thickened 

 in places. Sporangia typical of the genus, cylindrical, sympodially ar- 

 ranged, often bearing an oogonial branch below them. Zoospores as 

 usual. Oogonia typically racemosely borne, or also on main or sec- 

 ondary hyphae; spherical, with thorny, pointed warts over whole sur- 

 face; wall yellowish, diameter without spines 3i.5-46;i., with them 40- 

 54.5a. Spines ~-i2\i long, 9.5-12^1. thick at base. Eggs one, rarely 

 two, or more rarely three in somewhat elongated oogonia, filling the 

 oogonium. Egg membrane clear ^-ellow; contents thick, with numerous 

 large and small fat-drops [does not say whether centric or eccentric]; 

 diameter 29-39;Jl, mostly 34-36.5:0.. Antheridia on short bent stalks 

 from the oogonial stalk or the main hyphae; club-shaped, present on 

 most of the oogonia. Antheridial tubes nearly always present. In some 

 cases sporangia halt in development and after a while drop off, and 

 when brought into nourishing media sprout to hyphae. Typical gem- 

 mae not present. The species is nearest A. stellata deB., which it re- 

 sembles in the one-egged, spiny oogonia. In other ways it is quite 

 diff'erent. Found on the eggs of American brook trout, in the fish hatch- 

 ery at Munchhausen Reg. Bez. Cassel. 



Not only the above description, but the figures also, leave no doubt 

 of the identity of this species with those of Petersen and Minden. It 

 is also quite possible that the insufficiently described S. racemosa var. 

 spinosa Cornu is the same, but there seems no way to be sure. The 

 species is distinguished from A. colorata by the oogonia containing 

 but one egg as a rule and by the dense, sharp spines. Tiesenhausen 

 ('12, p. 283) finds two slightly different forms of A. radiosa and gives a 

 good figure of the ripe egg. He shows it (fig. 13) in section with oil drops 

 most of the way around (subcentric). For a good account of A. decorata 

 with figures and the results of numerous cultures and experiments, see 

 Obel ('10, p. 421, figs. 1-4). 



Achlya americana var. cambrica Trow. Ann. Bot. 13: 135, pis. 8-iO" 



1899 



Trow's description we append below: 



"Mycelium, as developed on house-flies, with main hyphae about 

 I cm. long, a maximum diameter at the base of 92J., and tapering grad- 



