either broad or nanroiv, traversed by a midrib which disappears opposite the 

 point where they separate from the principal leaf, and also below their 

 apices : these midribs, vanishing at base and apex, are found in all the 

 smaller subdivisions of the frond. The margin, especially in the narrower 

 varieties, is sharply serrulate. Cystocarps hemispherical, apiculate, one 

 on the rib of an ultimate lacinia, near its base. So7'i arranged along the 

 margin of the lesser lacinise, at each side of their costulse. Colour a rosy 

 red, often much diluted. Substance softly membranous, but not gelatinous, 

 bearing long immersion in fresh- water without injury. In drying the plant 

 firmly adheres to paper. 



This is one of the most variable of all the Australian Rhodo- 

 sperms, and also one of the commonest. Under all its varieties 

 it may be known by the peculiar nervation, the midrib failing 

 beloio the apex of the frond, and everi/ lateral nerve disappearing 

 opposite the base and below the apex of the lobe of the frond 

 through whose centre it runs. The margin is generally sharply 

 serrulate, but sometimes nearly entire. Sometimes the frond is 

 very coarse in texture, sometimes soft and delicate, sometimes 

 crowded with imbricating lobes and lobules, and sometimes laxly 

 and distantly laciniate. It would be a vain task to attempt to 

 describe or figure the varieties : the student will gradually re- 

 cognize the species under every mask, by keeping in mind the 

 characters of venation above pointed out. 



Fig. 1. Delesseria frondosa, — the natural size. 3. Apex of a frond, with 

 cystocarps in situ. 3. Vertical section of cystocarp and lamina. 4. Spore- 

 threads. 5. Apex of a frond, with sori. 6. A sorus, and part of the 

 membrane : — more or less magnified. 



