KEY TO THE GENERA OF THE ATLANTIC 



COAST. 



OLIVE GREEN ALG^. 

 I. Frond leaf-bearing. 



Main stem and branches cylindrical, bearing 

 globular, stalked minute, air vessels, and 

 narrow, undivided, dotted leaves. General 

 habit arborescent. " Gulf- weed." Sargassu?n. 



II. Frond, flat, coriaceous or leathery. 



I. With Midrib. 

 {a.) Frond perforated. Agarum. 



{b.) Frond entire, stem bearing leaflets or 



wings. Alaria, 



2. Without Midrib, 

 {a.) Frond thick, leathery and large, dark olive 



green or brown. ^'Kelp." Laminaria. 

 (b.) Frond thinner and smaller, light green or 



brown, from three to twelve inches 



long. Pimctaria. 



(c.) Frond narrow in proportion to length, 



half-inch wide, eight to twelve inches 



long. Fhylliiis. 



(^d.) Frond still narrower and constricted at 



intervals. ScytosipJion. 



