WITH IfOTES ON OTHER SPECIES. 



135 



Subfamily Leijtomiteai. 

 Leptomitus Agardh ('24). 



Syn.: Apodya Cornu ('72). 



Hyphse stout at the base, marked ofifat intervals by deep constrictions into dis- 

 tinct segments ; branching abaudant, dichotomoiis below, but often monopodial on 

 the finer ultimate divisions; branches arising only from the acroscopic ends of the 

 segments. Zoosporangia formed from swollen segments of the hyphse which are cut 

 off at the constrictions ; the primary ones from apical segments, and later ones often 

 several in basipetal succession. Zoospores biciliate, monoplanetic (?), swarming 

 separately. Oogonia and antheridia unknown. 



Leptomitus lacteus (Roth) Ag. ('24). 



Syn.: Conferva lactea Roth (1789). 



Saprolegnia lactea Pringsh. ('60). 



Apodya lactea Cornu ('72). 

 Exsic: Rabh., Algen Sachsens, 587. 



111.: Dillwyn, '09, PI. 



Pringslieim, '60, PI. XXIII. Figs. 6-10 ; XXV, 1-6. 

 Pringsheim, '83b, PL VII, Figs. 1-9, 

 Biisgen, '82, Pi. XII, Figs. 9-15. 

 PL XX, Figs. 115-118. 



Hyphse rapidly decreasing in diameter with successive subdivisions; apical seg- 

 ments about 10,a in diameter and often forty times as long. Zoosporangia cylindri- 

 cal, from slightly swollen segments, their mouths terminal or lateral. Zoospores in 

 a single file within them. 



Massachusetts — Amherst: Connecticut — Bridgeport, Holden. Europe. Prob- 

 ably common everywhere. 



This unmistakable form appears to be common enough in Amherst, and is un- 

 doubtedly so elsewhere in favorable situations. It prefers, as has been before inti- 

 mated, waters which are somewhat, but not too sti"ongly, polluted by organic 

 substances. I first met with it on masses of decaying Algae which had died and 

 broken down in the vessel in which they had been kept. Afterwards it appeared in 

 fly cultures from waters from the outlets of drains, containing decaying vegetable 

 matter. It does not appear to flourish where active decay of animal substances is 

 going on. In favorable places, it often forms very dense masses of closely felted 

 threads, covering very large surfaces. Goeppert observed ('52) such a case in a 

 small stream below a beet-molasses manufactory, near Schweidnitz, in Silesia. I 



A. P. S. — VOL. XVII. R. 



