Seu. GOXUYLOSrEKiMK.E. ( 183 ) Fam. CEKAMIACEiE. 



CALLITHAMNION TRIPINNATUM.— ^r/. 



Gen. Char. — Frouds filiform and articulated, sometimes at length in the older parts 

 cellular and partially opaque, single-tubed ; divisions mostly pinnate, dissepiments 

 hyaline. Fructification of two kinds, on distinct plants : 1. Favelloe, mostly 

 lateral on the branches, and filled with minute spores ; 2. Tetraspores, external, 

 tripartite or cruciate. Name from /caA^s, "beautiful," and ^a'^ui/ox, "a shrub." 



Callithamnion tripinnatum. — "Frond distichoiisly branched, capil- 

 laiy, decomposito-pinnate ; plunmles elongate obovate, tripinnate above ; 

 upper pinnre elongate and pinmilate, lower short or abortive, each pin- 

 nule having at its axil a minute pinnule ; pinnules long, setaceous ; 

 joints of the stem three to four times, of the pinna3 about twice as long 

 as broad ; tetraspores oval, lateral on the axillary, and occasionally on 

 the other pinnules." — Fhi/c. Brit. 



Callithamnion tripinnatum.- — Ac/. Sp. Alt/, vol. ii. p. 168; /. Ag. Alg. Medit. 

 p. 72 ; Endl. 3rd Suppl. p. 34, No. 23 (but not of Harv. in Hooh. 

 Br. Fl. vol. ii. p. 346, nor of Wyatt, Alg. Danm. p. ISO) ; Barv. P. B. 

 plate 77 ; Harv. Man. p. ISO; Harv. Byn. p. 152; Atlas, plate 56, 

 fig. 261 ; /. G. Agardh, Sp. Gen. Alg. vol. ii. p. 46. 



Mkrtensia tripinnata. — Gratel. 3IS. sec. Ag. 



Hab. — On marine rocks, at extreme low-water mark. Annual. April, May. Yery 

 rare. Eoundstone Bay {Mr. M'Calla) ; Plymouth {Mr. Rohloff). 



Geogr. Dist. — Coast of France ; Grateloup ; Mediterranean Sea (/. Agardh^. 



Description. — Fronds tufted, one to two inches high, very slender 

 and capillary, membranaceous not gelatinous, perfectly distichous, mostly 

 tripinnate ; pinnae acutely obovate or lanceolate, alternately pinnulate, 

 the lower pinnules short, mostly simple or with a single pinnule above 

 at the base, all cylindrical, tapering to a fine point ; the lower half of 

 the upper pinnules naked, the upper half again pinnate, with long, 

 slender, alternate pinnse, shorter upwards, and tapering to a point ; at 

 their base on the upper edge is a solitary short pinna similar to that on 

 the lower pinnidse. Artictilations of the stem and branches from three to 

 four times longer than broad, nearly cylindrical or slightly contracted 

 in the middle ; those of the upper divisions about twice as long as broad. 

 Favellae appear to be unknowai. Tetraspores oval, with wide borders, 

 secund along the edge of the ultimate pinnules, and most frequently on 

 the small solitary pinnse at the base. Substance delicately membranous, 



