NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 91 



Weeksia templetonii Setchell & Gardner 

 Plate 7, fig. 1 



Setchell & Gardner, 1937, p. 76, pi. 10, fig. 28. 



Thallus 8-12 cm. high, membranous, consisting of a single, mucilagin- 

 ous, flaccid, orbicular blade 200-250 fj. thick with a very short, slender 

 stipe attached by a small disc; blade with a few faint, radiating false 

 veins, but with no differentiation of tissues to form them ; medulla com- 

 posed of a network of more or less straight filaments of cells 5-7 [i in 

 diameter and 8-12 times as long as broad; subcortex of about 2 layers of 

 spherical or subspherical cells ; cortex of a single layer of slightly radially 

 elongate pigmented cells about 7 by 10 /x in dimensions and with a partial 

 inner second layer of more spherical cells of slightly greater diameter; 

 cystocarps numerous, very small, uniformly and generally distributed, 

 embedded; carpogonial branches curved, composed usually of 6-8 cells 

 about 7 ;u, in diameter; tetrasporangia broadly ellipsoid to subspherical, 

 cruciate, 18-22 /t by 22-26 fi in dimensions; antheridia unknown. 



Type: Holotype is Howell 703, Aug. 15, 1932, on sheet 236484 

 in the Herbarium of the California Academy of Sciences, San Francisco, 

 California. 



Type locality: At a depth of 38 meters off Isla Cedros, Baja 

 California, Mexico. 



No specimens other than the type have been obtained of this plant 

 in Mexico, but a specimen dredged off Santa Cruz Island, California, 

 agrees well with JVeeksia templetonii in habit and in all structural 

 measurements. It has been used here to illustrate the structure of the 

 species. 



Weeksia reticulata Setchell, from the vicinity of Monterey, Cali- 

 fornia, is a similar but apparently distinct species. Fresh material from 

 Monterey is not available, but transections of the dry type compared 

 with the Santa Cruz Island plant noted above show some structural 

 differences which may be significant. W. reticulata seems to have a some- 

 what more densely filamentous and perhaps thicker medulla than W. 

 templetonii. Its cortex seems thicker, and, rather than being composed of 

 a single outer layer of slightly elongated cells, is made up of short fila- 

 ments of 2-3 cells. Macroscopically the type of W. reticulata shows 

 prominent veins, and these probably represent the most effective differ- 

 entiating character at the present time. 



The specimen from Cabo Colnett, Baja California, referred to Week- 

 sia reticulata by Dawson, 1945b, has been critically examined by Dr. 

 Isabella Abbott and found not to be a Weeksia. 



