178 University of California Puhlications in Botany [Vol. 8 



lenticular, destitute of pyrenoids ; akinetes ( ? ) thick-walled formed 

 within the continuity of the filaments ; aplanospores large, ellipsoidal, 

 formed at the ends of the branches; zoospores large, formed at the 

 ends of the branches, provided with many cilia arranged in pairs 

 with a nucleus immediately beneath each pair; sexual reproduction 

 anisogamous ; antheridia tubular, usually curved, emitting many very 

 small uninucleated 2-ciliated male gametes; oogonia swollen, globular 

 to ovoid, sessile or pedicellate, single or several together, producing a 

 single large uninucleate non-motile female gamete amply provided 

 with chromatophores, fertilized in position ; monoecious or dioecious. 



Dumortier, Comm. bot., 1822, p. 71, Analyse fam. pi. 1829, p. 77. 

 Vaucherideae Gray, Arr. Brit. PL, vol. 1, 1821, p. 288. 



The family of the Vaucheriaceae, while simple in its coenocytic 

 structure and form of filament, is probably the most complex in its 

 reproduction among the Chlorophyceae. The zoospore is distinctly 

 coenocytic, being large and covered with cilia which, however, are 

 arranged in distinct pairs, each pair associated with its own nucleus. 

 The male gametes, on the other hand, and the female gametes, so far 

 as examined, possess at maturation only a single nucleus. They are 

 very different in size and, while the female gamete or egg is non- 

 motile, the sperms or male gametes are motile, with two equal cilia 

 widely separated and pointing in opposite directions. 



There are two genera usually included in the family, viz., 

 Vaucheria with continuous and unconstricted filaments and Dicho- 

 toniosiphon with more or less interrupted and constricted filaments. 



9. Vaucheria DC. 



Filaments continuous, without constrictions ; reproduction as indi- 

 cated for the family. 



De Candolle, Extrait d'un rapport sur les Conferes 1801. 



The genus Vaucheria includes both fresh-water and brackish-water 

 species. A few are truly marine. There are both marine and brackish 

 water species about San Francisco Bay, but careful search has as yet 

 failed to reveal any trace of sexual reproduction in these. Without 

 a knowledge of the details of this process, it is impossible to be certain 

 of their identification. Specimens of this genus are better preserved 

 for future study in formalin solution or in alcohol, since dried speci- 

 mens are difficult to restore to normal appearance on moistening. 



Otto Kuntze (1891, p. 926) raises the query as to whether 

 Vaucheria DC. or Ectoaperma Vauch. is the older name. "We are 

 unable to settle this question. 



