126 ARCHER, ON SAPROLEGNIEA. 
cumstance which points to the genus Achlya. In that genus 
the zoospores, besides being the products of a number of 
special mother-cells (not, as in Saprolegnia, primordial cells) 
formed from the contents of the sporangium, the sporangia 
themselves are, moreover, produced, one or more generations 
after the first, by being given off laterally at the base of the 
first (not terminal as in Saprolegnia, and the new sporangium 
being pushed up within its now empty predecessor). Now, 
may not this tendency, seeming inherent in Achlya, to put 
forth fresh growth laterally, when about to form new spo- 
rangia, be again evinced when about to put forth new 
oogonia? May not this kind of innovation, so to speak, be 
characteristic of the genus Achlya, so far as it is worth? 
The following may serve as a description of this plant: 
Achlya cornuta, sp. nov. Figs. 2—6. 
Plant diecious; oogonia large, mostly terminal, often in 
an uninterrupted series, the outer wall drawn out into 
numerous horn-like extensions of varying and often consider- 
able length, sometimes bifid; the apex of the terminal one 
drawn out generally very long, and occasionally the support- 
ing filament or stem giving off lateral branches by a kind of 
proliferous growth, each of which eventually terminates in 
an oogonium of similar character, but usually of smaller size ; 
oospores large, one or several in an oogonium; mother-cells 
of spermatozoids as in Achlya dioica. I have not been able 
to see any openings in the wall of the oogonium; they must 
doubtless exist, but the densely arranged cornua render the 
examination with this view very difficult. De Bary himself, 
in his Aphanomyces stellatus, found the same difficulty from 
the same cause. The uppermost oogonium is the oldest or 
first formed, the lowest the youngest or last formed, in the 
series. 
Here, as is seen, the oogonia occur in a continuous series, 
several being in succession separated merely by a septum, or 
they may be few or even solitary; they mostly terminate a 
filament, and rarely occur along its length. In this respect 
they differ, so far as I know, from those of other Saprolegniez 
recorded, except S. androgyna above described. But, if I am 
right, this form not only falls under a distinct genus from that 
just described above, but, even if the evidence were in favour 
of their belonging to one genus, they are abundantly speci- 
fically distinct in that the present plant is dicecious, the 
former monecious, and that on a seemingly novel plan. 
Moreover, A. cornuta is abundantly distinct, owing to the 
remarkable horn-like extensions, numerous and often long, 
and occasionally bifid, which are presented by this form; on 
7 ——E— Eee 
