158 THE SAPROLEGNIACEAE 



again as in Saprolegnia. Gemmae absent. Oogonia borne on short 

 lateral branches, small, smooth, subspherical, unpitted. Antheridia pyri- 

 form, diclinous. Eggs single, completely filling the oogonium, the proto- 

 plasm nearly surrounded by a surface layer of small droplets. There is 

 but one species known. 



Leptolegnia caudata deBary. Bot. Zeit. 46: 631, pi. 9, fig. 5. li 



Plate 54* 

 Mycelium delicate, flaccid, the hyphae little branched, about 10- 

 18 [J. thick; gemmae none; sporangia filamentous, of the same size as 

 the hyphae, often long but not so long as in Aphanomyces, about 15-18 x 

 325-880^1, sometimes branched; spores typically in a single row, irregu- 

 larly angled and lobed before discharge, becoming rod-shaped when 

 passing out; after emergence the two ends bending backward and fusing 

 to form a pip-shaped spore with two apical cilia; diplanetic, 12.5-13.5^1 

 in diameter in the resting state. Oogonia borne on rather short lateral 

 branches, subspherical with a slight beak, smooth and without pits, 

 30-40[j. thick. Eggs single with a more or less complete circle of periph- 

 eral droplets, completely filling the oogonium. Antheridia one or several 

 on every oogonium, short-pyriform, terminating slender branches of 

 diclinous origin. 



Rather rare, first found in an aquarium jar of algae that had been 

 brought into the laboratory from pools in the vicinity. Occurring in 

 0-7% of all Chapel Hill collections between February 15, 1912, and De- 

 cember 12, 1913, as in Terra Cotta spring. Glen Burnie farm, marsh 

 south side of Glen Burnie meadow. Arboretum brook, etc. Later it 

 appeared in several collections of material sent by R. S. Haltiwanger 

 from Avon Park, Florida, and in material collected by us near W^ilmington, 

 N. C. 



Found twice by deBary in mountain lakes in Germany in 1881 and 

 1884, the species has been reported but a few times since. Fischer 

 ('92, p. 346) refers to a sterile plant that he thought might be this species. 

 Minden ('12) found it often near Hamburg, Germany, and figures 

 it (figs. 4a and 4b on p. 556), and Petersen finds it in Denmark ('10, 

 p. 521). Dr. Roland Thaxter writes that he has seen a form without 

 sexual reproduction that resembled Leptolegnia ; and Dr. Pieters has 

 unpublished drawings of the characteristic sporangia from plants found 

 at Ann Arbor, Michigan. According to Petersen ('30, p. 511) this species 

 is a destructive parasite on the crustacean Leptodora Kindtii in Denmark. 

 He thinks that the mycelium usually enters around the opening of the 

 mouth, and that the infection is always fatal, enveloping the mother and 



* See Mycologia 1: 262, pi. 16, 1909, from which the plate and most of the description 

 was taken. 



