WITH NOTES ON OTHEE SPECIES. 109 



Their walls are occasionally pitted, and no antheridia are developed. A striking 

 feature is the separation of the oiigonia from the plant and from each other, often 

 at a very early stage, so that they lie free in the water and complete their develop- 

 ment independently. 



The species presents a transitional feature leading towards Achlya, or a rever- 

 sional feature towards the commonest condition in the family, in that many of the 

 later sporangia are produced by cymose branching, instead of by the usual method 

 for Saprolegma. It has not been seen in America. 



Saprolegnia diclina nom. uov. 



Syn.: S. dioica DeBary ('88). Ill-'- DeBary, '88, PI. X, Figs. 12, 13. 



nee S. dioica Pringsh. ('60), nee Scliroet. ('69). PL XVII, Figs. 50-53. 



Hyphse slender, not long. Zoosporangia nearly cylindrical. Oogonia terminal 

 on main hyphse, or less commonly on lateral branches, typically globular, their walls 

 marked with small pits, which are often few and inconspicuous. Antheridial branches 

 long, flexuous, and very slender, of diclinous origin. Antheridia on every oogonium, 

 ovate or short clavate, often very abundant and covering much of its surface, some- 

 times rather few. Oospores most commonly ten or twelve, sometimes twenty or 

 more, and often onl}^ four to six, centric, their average diameter about 25/y. 



Massachusetts — Amherst : Pennsylvania — Philadelphia, Keller : Alabama — 

 Auburn, AtMnson : Louisiana — St. Martinville, Langlois. Europe. 



This is unquestionably our commonest Sa{prolegnia. I have obtained it six or 

 seven times in cultures from small pools, spring-holes, and similar places, and have 

 received it from most of my correspondents, as above shown. It is readily identified by 

 the small and fewer pits of the oogonial wall, as compared with those of the ferax 

 group; and especially by the antheridia, which are always present, as in 8. monoica, 

 but smaller, of different shape, and on slenderer branches than in the latter species ; 

 while the branches are always of diclinous origin. When the plants become old, 

 these delicate antheridial branches often disappear, leaving the antheridia adhering 

 to the oogonia without indication of their origin. This may, indeed, happen in other 

 species, but not so commonly or so early as in the present one. 



A reduced form of this species, hardly worthy of varietal i-ank, occurs frequently. 

 It is distinguished chiefly by its smaller size, and by a reduction of the number of 

 both oospores and antheridia to a very few (Fig. 53). 



The species, as limited in America, is exactly 8. dioica DeBary, except that I 



