78 THE BOTANICAL MAGAZINE. [Vol. xxxi. No. m. 



given to the species of Iridsea by the former writers were by no 

 means complete or satisfactory, and the distinctions between 

 many of them were hardly apprehensive. What we could rough- 

 ly estimate of the number was that there occur in the North 

 Pacific several forms of Iridsea passing by degrees to I. cordata 

 (Turn.) and in the South Pacific, also several, resembling to 

 I. laminarioides Bory. This conception, however, was over- 

 turned by Setchell and Gardner 1 ' who have jointly treated 

 these two species as mere forms of one and the same species. 

 The combination as they have done may be open to criticism 

 but it is not to be denied that too many species of Iridsea have 

 been established by the old writers. 



In Japan, species of Iridsea are used for sizing the textiles 

 and for other purposes. They are collected in large quantities 

 and dried in the sun. The Iridsea harvest is one of the import- 

 ant seaweed industry in the northern Japan. In the markets 

 thej'- are classified into various grades according to the sources, 

 size of fronds, luster, etc. Study of species of Iridsea is hence of 

 industrial importance in Japan. 



It is not the aim of the present paper to criticise all the. 

 North Pacific species of Iridsea. I have but to repoit here the 

 occurrence in Japan of some species and forms already described. 

 It is to be understood that we have some more forms not un- 

 able to determine at present or certainly not yet described ; 

 and also that the forms here related may be dealt with in some 

 other wa} ? when we have thoroughly revised all species of 

 Iridsea hitherto known. 



var. cornucopise J. Ac. 



Spec. II, p. 253— Id. : Epicris, p. 180. 

 -Iridsea cornucopia? P. et R. : Ulustr. Alg., p. 18, (excl. var.) PI. 



XXXVIII, fig. b. 

 = Iridsea phyllocarpa P. et R. : Ulustr. Alg., p. 18. 

 — Chondrus phyllocarpns Rupr. : Tange des och. Meeres, p. 316. 

 = Iridsea laminarioides f. parvtrla Kjellm. : Beringhafv., p. 31. — 



Setch et Gardn. : AJg. N. W. Amer., p. 299. 



1) Alg. of N. W. Amer., p. 299. 



