24 ART. 12. — K. YENDO. 



DcNE., and Areschoüg/^ without hesitation, assigned the species 

 to the genus Amphiroa. 1"^ have enumerated it under the genus 

 Amphiroa but with much uncertainty. The fronds have both 

 sorts of articuli, the homogeneous cylindrical ones and the com- 

 pressed reniform. These forms occur in different branches separately 

 but frequently in the same branch. Cf. PI. LI. " Cor. ver. Port 

 Renfrew." The conceptacles are always found upon the flattened 

 articuli, in the same manner as is characteristic of the Alatocladia. 

 This character suggests Cheilosporum much more than it does 

 Amphiroa. The microtomic section of the fertile articuli shows 

 some conceptacles originate deep in the medulla and some ap- 

 parently in the cortex. This fact greatly perplexed me in dis- 

 tinguishing the generic position of the plant, but I provisionally 

 followed the opinion of Endlicher,^* and reckoned it under 

 Amphiroa. The reader may notice that the diagramatic figure^^ 

 of the cross section of the articulus with four conceptacles is the 

 only one figure in my former papers which does not give the 

 boundaries in the fine dotted line between the medulla and the 

 cortex. The origin of the spores in this species, as above men- 

 tioned, is uncertain in some degree. But the presence of the 

 conceptacles exclusively on the compressed articuli is a character 

 which suggests disposition as above. It might well be considered 

 as a transitional form linking the Alatocladia to the Arthrocardia. 

 The reduction of a species to a forma or variety of a distinct 

 species depends upon the view of the author. A character may 

 be taken as specific or as formal. No one can judge which should 



1) J. Ag. : Spec. Alg. II. p. 538. 



2) Cor. ver. Port Renfrew, p. 714. 



3) Mantissa.iSuppl.lIII. p. 49. 



4).. Cor. ver.^Port Renfrew. PI. LVI. fig. 1. 



