10 THE MARINE BOTANIST. 



HALIDRYS SILIQUOSA. — POD -BEARING 

 HALIDRYS. 



The fronds of this plant vary from one to four 

 feet in length, the branches are narrow and set 

 in the upper part with the long flattened pod-shaped 

 air-vessels and receptacles. Colour dark olives- 

 black when dried. Substance tough and leathery. 

 Perennial. Winter and Spring. Common on rocks 

 and stones in the sea, at and below half-tide level. 

 The var. /3 minor smaller in every part, with fewer 

 air-vessels, is found in shallow pools left by the 

 tide. 



CYSTOSEIRA. 



Name meaning a chain of air -vessels, in allusion to the 

 disposition of the vesicles in these plants. 



Frond much branched, occasionally leafy at 

 base ; branches becoming more slender upwards, 

 and containing strings of simple air-vessels within 

 the substance. Heceptacles small, terminal. 



