Ser. RiiODOSPERME^. Fam. llhodonidacece . 



Plate CXXVII. 



, MARTENSIA DENTICULATA, iiarv. 



Gen. Char. Frond substipitate or sessile, membranous, nerveless, fringed 

 (at maturity) with an open network, formed of vertical and horizon- 

 tal anastomosing bars and cross-bars. Frnctlfcation : 1, ceramidla, 

 containing, within a membranous pericarp, a dense tuft of pear-shaped 

 spores; 2, tetraspores, usually lodged in the cross-bars of the net- 

 work. — Martensia [Hering], in honour of Professor Martens, of 

 Brussels. 



Frons substijntata v. sessilis, memhranacea, enervis, areolata, infra marginer/i (m 

 cetate rnajorej clatlirato-fenedrata ; reticido ex trabecuUs vertlcalibus et ho- 

 rizontalihusforinato. Fr?ict.:l, cermnidia ; 2, tetrasporce triangule d'mscB, 

 in laminis vertlcalibus reticuU immersa. 



Martensia denticulata ; fronds sessile, tufted, delicately membranaceous, 

 repeatedly dichotomous; segments cuneate, the uppermost very often 

 flabelliform ; margin curled and denticulate ; upper margin of the 

 network ciliate, dentate or lobulate, the lobules at length elongate 

 and fenestrate. 



M. denticulata ; frondibus sessilibus ccespitosis temussime membranuceis repetite 

 dichotomis, laciniis cimeatis nllimis non raro jiabelliformibus, margine crispato 

 detdiculato, reticido apice ciliato, deuticulato v. lobato, lobulis deinum elon- 

 gatis feuestratisque. 



Martensia denticulata, Harv. in Trans. R. I. Acad. v. 22. p. 537. Harv. 

 Alg. Austr. Fxsic. n. 113. 



Hab. On rocks and Algse, at extreme low-water mark. Garden Island, 

 Rottnest Island, Eremantle ; frequently cast ashore in winter, JF. H. II. 

 G. Clifton. 



Geogr. Distr. Western Australia. 



Descr. Root discoid. Fronds densely tufted, quite sessile, 2-3 iuclies long, 

 as much in expansion, repeatedly forked, with rounded but narrow axils, 

 fastigiate ; the segments linear-cuneate, the uppermost often obovate or 

 orbicular. Margin wavy, irregularly but sharply denticulate, rarely suben- 

 tire or remotely toothed. Netioork gradually formed at the end of the 

 branches, finally extending about \ or f down their length, composed of 

 very slender vertical and horizontal bars ; the uppermost margin toothed 

 or ciliate ; the teeth, in old specimens, frequently lengthen into small linear 

 lobes, which sometimes bear secondary networks at their apices. The ra- 

 mification of the frond is very variable, and so is the proportion of the divi- 

 sions to each other. Ceramidia (very rare) sessile on the network, ovate- 



