VAUCHERIA. 147 



Oogonium lateral, sessile, or borne on a more or less elongated, 

 simple or partite pedicel ; cytioplasm at length converted into a 

 large oospore. 



Antheridiuni lateral, sessile, or cut off by a septum from the 

 upper portion of a lateral branch, in which numerous spermato- 

 zoids are generated, which at length become free 5 spermatozoids 

 oblong, furnished, except in one species, with two unequal cilia. 



Genus 30, VAUCHEEIA, D. C. 



The generative cells, the oogonia and the antheridia are devel- 

 oped in various numbers on the same filament, or tube. They 

 are either sessile or posed on short pedicels, and are usually in 

 close proximity, but in various relative positions. The oogouia 

 are somewhat globular, one side beaked, opening at the apex ; 

 the antheridia are more or less cylindrical, curved, horn-like in 

 the upper part, the ends usually so turned that the apices are 

 directed towards the beak of the oogonia. 



The spermatozoids are developed in the curves of the anthe- 

 ridia and ejected towards the mother cell and drawn in at the 

 beak ; the oosphere is thus fecundated and becomes an oospore. 



Zoospores are developed, singly, in the terminal sporangium 

 and ejected from it. They move with a rolling motion by means 

 of cilia with which their whole surface is amply provided, but 

 soon come to rest and germinate. 



Microgonidia are developed in large numbers in vegetative 

 cells ; they are ejected but remain motionless, at rest, soon to 

 germinate. 



The following list is in accord with an arrangement of Euro- 

 pean species, proposed by Professor Nordstedt, of Sweden. 



A. Antheridia not separated from the thallus by a short empty 



boundary cell. 



a. TUBULIGER^E. Antheridia little or scarcely bent, oblong 



cylindrical, or lanceolate, with an opening at the top. 



Oogonia and antheridia almost steniless. 



Oogonia nearly round. 



1. V. dichotoma, Linn. Dioecious. 



2. V. Thuretii, Woron. Monoecious. 



Oogonia not round, more or less oval, frequently rather oblique. 



3. V. aversa, Hass. 



4. V. siricea, Lyngb. 



