26 ' 



in the western coast of Kamchatka, some 35 miles north of C. Lopatka. 

 The present plant has a strong resemblance with Odonthalia 

 semicostata illustrated in Setchell and Gardner's Algae of North- 

 western America p. 336, pi. 26,27, in having closely arranged 

 alternate dentiform to subulate lacineae along margins of branches ; 

 but the mode of ramification and presence of axillary branches 

 differ from it. The authors illustrate regularly alternate branches 

 which have no pinnule standing in axils and the substance is said 

 as thick. J. Agardh (I.e.) describes Oct. semicostata Mert. from 

 Kamchatka as having thin membranaceous frond bearing minute 

 pinnulae in axils. Collins (The Mar. Alg. of Vancouver Island, 

 1913, p. 122) considers Setch. and Gardn.'s plant as a species 

 different from that of J. Agardh, probably on account of thicker 

 substance, alternate ramification and absence of axillary pinnulae. 

 Taking into consideration the lacality of Mertens' plant is same 

 as that of ours which has much resemblance with J. Agardh's 

 descriptions, I refer our plant to the present species, though I have 

 not seen any reliable specimen or illustration of the species. 



PL. CLVII, fig. 1-6. Fig. 1 : sterile frond of Odonthalia semicostata 

 (Mert.) J. Ag. on the frond of Ptilota asplenioides, \. Fig. 2 : holdfast em- 

 bracing the frond of Pt. aspl&doidcs, a ; 2_2. fig 3 : growing apex of 

 frond ; a, apical cell ; l>, b' , lacineae ; 5JL. pjg 4 : cross-section of frond ; 

 c, central axis ; d ' , vein ; ^$. Fig. 5 : costal portion of fig. 4. magd.; c t 

 central axis ; ^2. Fig. 6 : longitudinal section of frond, ^-8. 



Odonthalia* semicostata (Mert.) J. Ag. 

 g* CLVII HJK, i-6H. 



" %,* - * 7,*!K*ft 3 9 at *,f5ljR - v f (g 



* Odonthalia Lyngb., I |f !> & \ Jg, / ft g ^^ H %. 144 ^ = 



