PLATE XVIII. 



Tolypella prolifera Leonhardi. 

 pia. 

 1. Plant, two-thirds natural size, from Ramsey St. Mary, 

 Huntingdonshire. 

 2, 3. Apices of dactyls, x c. 40. 



4. Fruiting branchlet. x c. 25. 



5. Oogonium, x c. 40. 



6. Oospore, x c. 40. 



