HOW TO KNOW THE SEAWEEDS 



20a Medulla containing slender, more or less longitudinal filaments 

 aggregated in the center of a parenchymatous tissue. Fig. 33. . .21 



iM^( 



Fig. 33. Agardhiella coulteri (Har- 

 vey) Setchell 



The inner medullary part of the 

 thallus as seen in cross section 

 showing the large, thin-walled, 

 parenchymatous cells surrounding 

 the central core of slender, elon- 

 gated, relatively thick-walled fila- 

 mentous cells. 



Figure 33 



20b Medulla entirely of more or less isodiametrical cells. (See Fig. 22) 

 22 



21a Branches relatively slender, narrow at the base and gradually 

 tapering to the apex. Figs. 33, 34 Agardhiella 



Fig. 34. Agardhiella tenera 

 (J. Agardh) Schmitz 



A small mid-portion of a 

 plant, X 1.4. This species is 

 abundant below low water 

 level along the Atlantic 

 Coast south of Cape Cod 

 and along the Gulf of Mexi- 

 co. Another species of more 

 robust habit, A. coulteri (Har- 

 vey) Setchell, occurs along 

 the entire Pacific Coast. 



Figure 34 



39 



