Marine Algae.] SUBANTARCTIC ISLANDS OF NEW ZEALAND. 503 



Class KHODOPHYCEAE. 



Earn. BANGIACEAE. 



PoRPHYRA, C. Agardh, 1824. 

 Distribution. — All seas. 



Porphyra perforata, J. Agardh. 



Porfhyra perforata, J. Ag., Till. Alg, Syst., iii, p. 69, 1882. 



* The Snares ; R. M. L, Campbell Island; R. M. L. (California, Valparaiso ?) 



The New Zealand species of Porphyra are inadequately defined, and until the 

 species and subspecies of the mainland are properly delimited in the light of modern 

 research it will be impossible to do more than state more or less crudely the species 

 of the outlying islands. As is well known, the older investigators were content to 

 define by means of their external shape and other superficial characteristics the 

 species of Porphyra obtained by them ; but the form, and sometimes even the con- 

 sistency, of the plant frequently depend upon the environment and upon the accidents 

 of its life, so that in many cases they are quite unreliable for diagnostic purposes ; 

 and until the type specimens of the older writers have been examined with modern 

 thoroughness it is impossible to give anything like an accurate synonymy of the 

 species. What follows is therefore only to be regarded as an endeavour to get a 

 little closer to a correct appreciation of the New Zealand forms than has hitherto 

 been attempted. 



Harvey attributed three species of Porphyra to New Zealand waters P. 



laciniata, C. Ag. ; P. vulgaris, C. Ag. ; and P. capensis, Kiitzing. Of these, P. 

 laciniata and P. vulgaris are probably the New Zealand forms or subspecies of the 

 common cosmopolitan species, called by many names. P. capensis does not occur 

 in New Zealand, but was reported because Harvey wrongly identified P. columbina, 

 Mont., with the South African P. capensis, Kiitz. These two species are undoubtedly 

 quite distinct. An authentic specimen of P. capensis which I have, collected by 

 Becker, differs widely from any local form, and therefore P. columbina, Mont., must 

 be restored to specific rank. 



In J. G. Agardh's( ^ ) list of New Zealand seaweeds, P. laciniata and P. vulgaris 

 are again recognised as local species; but subsequently( ^ ) P. laciniata is defined as 

 a variety of P. umbilicalis, L., and its habitat is restricted to the North Atlantic 

 waters ; whilst P. vulgaris appears as a synonym for the variety a purpurea, Roth., 

 of P. umbilicalis. In his classification of the genus, Agardh divides the species 

 into two divisions — those that are monostromatic and those that are distromatic. 

 This distinction, however, is admittedly to be used with circumspection, as a species 

 at one stage monostromatic may at another stage or in another part be distromatic. 

 On page 62, Agardh {loc. cit.) creates for New Zealand a new monostromatic species, 

 P. nobilis, and revives P. columbina, Mont., for certain distromatic forms from our 

 coast. 



(^) De Algis Nov. Zel. marinis, p. 1, 1877. 

 (2) Till. Alg. Syst. (vol. iii), vi, p. 63, 1882. 



