Distribution of the Laminar iacece. 375 



The simpler species of the genus Laminaria present the essential 

 features of kelp-structure in their simplest form. All the species 

 of the Laminariacese (with the exception of Chorda) in their earlier 

 stages of development resemble very closely such a species as 

 Jjaminaria Phyllitis (Stackh.), J. Ag.^ and then proceed to differen- 

 tiate along their several different lines. Within the genus Lamin- 

 aria itself there is considerable differentiation from the simple type. 

 Among the digitate species we may, perhaps, find a suggestion as to 

 the way in which the L^essonia- and Macroci/stis-tj^Q^ have arisen, 

 while the peculiar outgrowths at the base of the blade of L. radicosa, 

 Kjellm. may be of interest when compared with the method of origin 

 of the sporophylls among the Ecklonese and through them, of the 

 Alariese. The Agarese seem to be more closely connected with the 

 Laminaria-speG\es than any of the other subtribes. 



As to the modifications of the different genera in the several sub- 

 tribes, as much as can safeh'' be said, has been mentioned in con- 

 nection with the discussion of the classification. 



The writer wishes to acknowledge his deep obligations to Prof. 

 W. G. Farlow, of Harvard University, in whose laboratory and with 

 whose assistance much of the work leading up to the present paper 

 was done. He is also deeply indebted to Prof. D. C. Eaton of Yale 

 University for access to books and specimens, to Professors A. E. 

 Verrill, S. I. Smith, and W. H. Brewer of Yale University for valu- 

 able suggestions, and to Dr. C. L. Anderson of Santa Cruz, Cal., 

 Mr. F. S. Collins of Maiden, Mass., and Mr. Isaac Holden of Bridge- 

 port, Ct., for supplies of specimens. 



