NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 87 



Type: Holotype not designated, but represented by a specimen 

 collected by Draparnaud and sent to Lamouroux, probably now in the 

 Lamouroux herbarium at the Botanical Institute, Caen, France. 



Type locality : Near Montpelier, Mediterranean coast of France. 



Mexican distribution: Gulf of Calif. — D. 1888, Puerto San 

 Carlos, May; D. 7152, Puerto Escondido, Mar.; E. Palmer, Isla Car- 

 men; D. 7026, Bahia San Gabriel, Isla Espiritu Santo, Mar.; D. 3471, 

 Bahia de La Paz, Nov. Revillagigedo Archip. — ^Taylor 39-52, Bahia 

 Braithwaite, Isla Socorro, Mar. Guerrero — Hubbs 46-244, Acapulco, 

 Sept. 



This is a strictly tropical plant whose habitat seems to be confined to 

 quiet, warm lagoons subject to little wave agitation. 



Dumontiaceae 



Key to the Mexican Genera and Species 



1. Thalli membranous JVeeksta 3 



1. Thalli terete, polystichously branched . . Leptocladia laxa 

 1. Thalli compressed, with tapered margins, distichously branched 2 

 2. Transection showing a single prominent central axial fila- 

 ment; cystocarps scattered through mature parts 



Leptocladia binghamiae 



2. Transection showing a central axial filament and one or more 



similar filaments on either side; cystocarps aggregated in 



swollen tips of ultimate branches . . Pikea calif ornica 



3. Plants 8-12 cm. high; carpogonial branches of 6-8 cells about 7 



/I in diameter W. templetonii 



3. Plants 20-30 cm. high; carpogonial branches of 7-9 cells 10-13 

 p. in diameter fV. hoivellii 



Pikea callfornica Harvey 



Plate 6, fig. 6 ; Plate 23, fig. 1 



Harvey, 1853, p. 246; Harvey, 1858, p. 131, pi. 49, fig. B; Smith, 

 1944, p. 202, pi. 46, fig. 3. Pikea nootkana as employed by Doty, 1947, 

 p. 164; Dawson, 1949, p. 222. 



Thalli bushy, to 1 1 cm. high, usually consisting of a single deliques- 

 cent axis from a simple discoid holdfast ; axis repeatedly and rather dense- 

 ly and irregidarly alternately, distichously branched in 4-5 orders, about 

 1 mm. in diameter below and compressed with tapered margins, short 

 fusiform in transection, gradually narrower toward the ultimate branches 

 which may be only 250-500 /* in diameter and compressed but not much 



