16 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



All of the reproductive specimens of Porphyra naiadum examined 

 from Mexico and from southern California (La Jolla; Cardif) show 

 asexual spores being produced in abundance along the margins and distal 

 parts of the blades. Unlike the above varieties heretofore recognized, these 

 specimens have the spores in groups of four according to the formula 

 ^, ?., l^ The division parallel to the thallus surface appears to be sus- 



a b c 



pended so that the spores as released are elongate, about tv\7ice as long 

 as broad or a little more. 



At Bahia de San Quintin an abundance of P. naiadum var. australis 

 occurs on Zostera marina as well as on the usual host. These plants 

 are of relatively large size and luxuriant growth, averaging 2.5 cm. 

 high and reaching 4.2 cm. occasionally. In the same region it occurs also 

 on Phyllospadix, though on this host it reaches a maximum of only 3.0 

 cm. in height. No differences in spore-characters could be found between 

 plants on the different hosts at this locality, although the large examples 

 on Zostera closely resemble those of var. naiadum from central and 

 northern California. 



The southern limits of var. naiadum and the northern limits of var. 

 australis are probably to be found among the northern California Chan- 

 nel Islands and in the vicinity of Point Conception on the coast. A de- 

 tailed examination of the species is needed in this area, for specimens 

 examined from Santa Rosa Island agree with var. naiadum, whereas 

 some from Santa Cruz Island are of var. australis. 



The Porphyra naiadum reported by Taylor, 1945, from Costa Rica 

 represents a small but fertile example of P. thuretii. 



Porphyra pendula sp. nov. 

 Plate 13, fig. 2 



Thallis linearibus vel ligulatis ad 25 cm. longis, 3-12 mm. latis, 

 flaccidis, pendentibus, marginibus crispis ; laminis monostromaticis, ple- 

 rumque simplicibus; dioeciis; areis fertilibus marginalibus, continuis; 

 128 antheridiis in fasciculis singulis secundum formulam i, 1, ^; 8 



a b c 



carposporis in fasciculis singulis secundum formulam^ , 1, A. 



a b c _ 



Thalli saxicolous, membranous, attached by a very small disc, pale to 

 bright rose in color; blades usually simple, but sometimes divided near 

 the base into two or more parts, linear-ligulate, flaccid, pendent, to 25 

 cm. long, 3-12 mm. wide, the margins mostly prominently ruffled, gradu- 

 ally acuminate to the apex, monostromatic, 45-50 ii thick, of irregularly 

 shaped cells 7-11 /* greatest surface diameter, about 22-25 /a deep; plants 

 dioecious; antheridia in packets of 128 according to the formula i, i, ? 

 borne in a continuous, yellowish zone on either margin and including 



