XVII. OBSERVATIONS ON ALARIA NANA SP. NOV. 



Herman F. Schrader. 



Introduction. 



The genus Alaria is represented at the Minnesota Seaside 

 Station by at least two species. The larger of these, Alaria 

 cor data Tilden, is chiefly found in the same zone as Egrcgia 

 and various species of Laminaria, attached to rocks which are 

 seldom exposed except at low tide. It often reaches a length 

 of six feet or more. 



The species on which these observations are based, is found 

 only among the Postelsia?, attached to rocks which are seldom 

 submerged completely, except at high tide, but which are always 

 exposed to surf. 



Part of the general morphology was studied from fresh 

 material, but most of these observations are based on preserved 

 material, collected by the writer, at the Minnesota Seaside Sta- 

 tion during July and August, 1902. 



Distribution. — The genus Alaria was founded by Greville 

 in 1830. At present, according to Kjellman, eighteen or nine- 

 teen species are recognized, most of which are North Pacific 

 and Arctic. Three species are North Atlantic, one of them ex- 

 tending as far south as the coast of Ireland and of France (De 

 Toni, Alaria esculenta). 



General Morphology. 

 The young plants are usually found growing among the 

 branches of the holdfast of maturer forms of their own species, 

 or of Postelsia falmazformis , along with other young kelps, 

 coralline alga? and acorn barnacles. The writer succeeded in 

 collecting young specimens, less than two centimeters long, 

 others, a little more mature, showing the first appearance of the 

 gonidiophylls, and also mature specimens in all conditions. 

 The species under discussion is small, for two of the most typi- 



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