254 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 3 



plant another specific name and to dedicate it to that Prince of Phycol- 

 ogists, Gustav Thuret. 



The specimen from the Gulf of California referred by Howe (loc. 

 cit.) to this species has been re-examined, and his statements can here be 

 confirmed. It is undoubtedly very closely related if not identical with the 

 plants of the outer California coast. He also noted a difference from the 

 European plants, but followed Hus in his determination. Howe's plant 

 was collected at San Felipe Bay by MacDougal, February, 1904, and 

 described as follows: "Thallus monoecious; antheridia in spots and 

 streaks adjoining sporocarps, both unmixed with vegetative cells; carpo- 

 spores 8; spermatia 64; thallus disintegrating and deliquescing when 

 dried specimens are soaked in fresh water." 



Resembling the true Porphyra leucosticta, P. Thuretii also seems to 

 be a spring annual. 



In relationship, P. Thuretii seems closer to the distromatic species as 

 regards the smaller number of spermatia and carpospores. Rosenvinge 

 ( 1909) says that the number of spermatia in P. leucosticta is often smaller 

 than 64 from each mother cell, and that "the carpogonia produce 4 and 

 8 spores in two layers." 



We are here considering Porphyra leucosticta and P. Thuretii as two 

 monostromatic species, closely related taxonomically, but widely separated 

 geographically. 



Family Ghantransiaceae 



The plants of this family are small, even to microscopic, and unless 

 they occur in quantity on a given host or other substrate, most of them are 

 very easily overlooked. Consequently, many more species may be expected 

 in the Gulf of California than have thus far been detected. 



It has been considered advisable to use the genus Rhodochorton in the 

 more expanded sense (Drew, 1928) in the designation of the species thus 

 far known from the Gulf. 



Genus RHODOCHORTON (Naegeli) Drew 



Rhodochorton microscopicum (Naeg.) Drew 



Plate 41, Fig. 3 



Drew, 1928, p. 163. Callithamnion microscopicum Kiitzing, Tab. Phyc. 

 XI, pi. 58, fig. 2. 



