THE GREEN ALGAE OF NORTH AMERICA 421 



robust, up to 12 cm. high, ramuli imbricate, very dense. Ram-' 

 uli clavate with rounded or hemispherical summit, or sometimes 

 cylindrical. 



Forma TYPICA Weber, 1898, p. 366. Ramuli with swollen 

 summit, turned more or less to one side. Fla., W. I. 



-litstralian, Indian and Pacific Oceans, 



Var. LAMOUROUXII (Turn.) Weber, 1898, p. 368. Frond tall, 

 up to 16 cm., with distichous, alternate, subopposite, or scat- 

 tered, pyriform or clavate ramuli. Guadeloupe. 



Red Sea, Pacific. 



Var. GRACIUS (Zan.) Weber, 1898, p. 370. Frond slender 

 and elongate, often creeping, with rare cylindrical ramuli, or 

 with a considerable number of small clavate ramuli. Sand 

 Key, Fla. 



Possibly only a depauperate form of C. racemosa. 



15. C. PET/TATA (Turn.) Lamouroux, iSoga, PI. Ill, fig. 2 ; 

 Weber, 1898, p. 373, PI. XXXI, figs. 9-11 ; XXXII, fig. 8 ; C. 

 inacrodisca Phyk. Univ., No. 374. Stolon naked, creeping, 

 branched, robust or delicate ; frond delicate, simple or branched, 

 with simple, peltate, scattered ramuli, with a diameter of 3-8 

 mm., usually 3-5 mm. 



Var. TYPICA forma IMBRICATA (Kjellman) Weber, 1898, p. 

 375. Central axis of the frond surrounded by very dense 

 ramuli. W. I. (T5-pe and forma imbricata.} 



1 6. C. AMBIGUA Okamura, 1897, p. 4, PL I ; Weber, 1898, 

 p. 388; Vickers, 1908, p. 25, PI. XXXVII ; Okamura, Algae 

 Japonicae Exsicc., No. 95. Stolon wanting ; frond attached by 

 rhizoids, minute, filiform, solitary, erect, divergently branched, 

 with not very closely set, subdistichous or multiseriate ramuli 

 of diameter about equal to that of the axis, cylindrical or 

 slightly clavate, slightly or not at all contracted at the base. 

 Barbados. Japan. 



The smallest species of the genus and remarkable for the 

 total absence of the stolon. It is hardly likely that it occurs 

 only at the two widely separated stations now known, but it has 

 probably been overlooked elsewhere on account of its small size. 



Family 6. VAUCHERIACEAE. 



Fronds filamentous, cylindrical or with frequent constrictions, 

 with lateral or dichotomous branching ; chromatophores small 

 disks, without pyrenoid ; asexual reproduction by large, multi- 

 ciliate zoospores ; also by aplanospores and akinetes ; sexual 

 reproduction by oogonia and antheridia. 



