1^--'^] SetclieU-Gardner: Mehmophijceae 668 



separate individuals in specialized cavities among the so-called para- 

 physes. The reproduction is heterogamous and fertilization takes 

 place after the escape of the gametes. The female gametes (eggs) are 

 non-motile, and the male gametes (antherozoids) are motile by two 

 laterally placed cilia of unequal length. The inequality in size of the 

 gametes is very marked, the female having been estimated in some 

 cases to be thirty thousand times as large as the male. 



Areschoug {he. cit.) used the name as an order under the sub- 

 class Fucaceae, as he interpreted that group, and included four 

 genera, viz., Halidrijs Lyngb., Halicoccus Aresch., Fiicus L., and 

 Himanthaha as occurring in the region covered bv his account. 



Order 8. FUCALES oltmanns 



Fronds extremely variable in size, from a few centimeters to 

 several meters long, but usually slender, complanate, cylindrical, sub- 

 cylindrical or tumid and constricted at regular intervals, branched, 

 the branches either pinnate in two ranks in one plane (Fucaceae) or 

 arising on all sides of the main axis (Sargassaceae) ; attached by a 

 well developed, solid, usually disk-shaped holdfast, perennial, fruiting 

 annually and then the specialized fruiting parts disintegrating ; recep- 

 tacles limited to the terminal or subterminal parts of the fronds, the 

 oogonia producing 1, 2, 4, or 8 non-motile gametes (eggs). 



Oltmanns, Morph. u. Biol, der Algen, vol. 2, 1922, p. 186. 



Key to the Families 



1. Frond differentiated into axial and lateral members 25. Sargassaceae (p. 704) 



1. Fronds flattened without differentiation into axil and lateral members 



24. Fucaceae (p. 663) 



FAMILY 24. FUCACEAE lamour. (lim. mut.) 



Members of the order Fucales with flattened fronds not differen- 

 tiated into axial and lateral members. 

 Lamour., Essai, 1813, p. 8, in part. 



Key to the Geneka 



1. Fronds with distinct percurrent midrib 2 



1. Fronds without midrib 3 



2. Oogonium producing 8 viable gametes (eggs) 65. Fucus (p. 664) 



2. Oogonium producing 1 viable gamete (egg) 68. Hesperophycus (p. 703) 



3. Oogonium producing 2 viable gametes (eggs) (Xl. Pelvetia (p. 700) 



3. Oogonium producing 1 viable gamete (egg) 67. Pelvetiopsis (p. 702) 



