214 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.3 



of a long-handled rake from a skiff. The only form thus far known is that 

 which has been called C. sertularioides f. longiseta (J. Ag.) Weber-van 

 Bosse (B0rgesen, 1913, p. 133). 



D. 563, on sand bottom with coral clumps, shallows of San Gabriel 

 Bay, Espiritu Santo Island, Feb.; D. 574, dredged in 6-12 meters, 

 same locality; D. 618, abundant on mucky bottom of oyster-culture ponds, 

 forming extensive mats with C. racemosa var. uvifera, same locality. 



Family Godiaceae 



Genus HALIMEDA Lamouroux 



Halimeda discoidea Decaisne 



Decaisne, 1842a, p. 102; Howe, 1907, pp. 495-500, pi. 25, figs. 11-20, pi. 

 26; 1911, p. 492; Setch. & Gard., 1920, p. 177, pi. 13, fig. 3; 

 1924, p. 704. 



This species is reported thus far only from the warm waters of the 

 southern part of the Gulf. Three veiy early collections were made at La 

 Paz. H. 724, dredged in 40 meters off San Jose del Cabo, August ; D. 519, 

 dredged in 30-40 meters over sand bottom at Puerto Refugio (the most 

 northern locality). 



Halimeda discoidea is here near or at the northern boundary of its po- 

 tential area. None of the specimens collected are of the size and vigor of 

 examples from Central America and other parts of the Pacific. It has al- 

 ready been suggested that low calcium content of the Gulf sea water may 

 in part account for their scanty development. 



Genus GODIUM Stackhouse 



In 1924, when Setchell and Gardner wrote their account of the Gulf 

 species, only a few collections were available, and nothing was recorded 

 on the ecology of the various species or of their appearance in nature. Since 

 the preservation of material by drying destroys much of the normal aspect 

 of these plants, unless one has some experience with the species of a par- 

 ticular region it is difficult to visualize the nature of the plants from the 

 dried specimens. The recent experience of the author in the field and the 

 somewhat more extensive collections have made possible a revision of the 

 several Gulf Codium species from a different point of view. 



The author considers utricle shape-characters of secondary importance 

 in distinguishing the species at hand, for considerable variation due to age 

 and habitat may occur in the same plant. Indeed, utricles of various ages. 



