512 Transactions of the Society. 



Potamogeton crispus has an ellipsoid pollen, in some species 

 resembling a boat turned up at the end, and the sides are pro- 

 duced sometimes even overlapping. 



Ajwnogeton is decidedly entomophilous, and the pollen closely 

 i-esembles that of Potatnogeton. 



That of Zostera is a cylindrical tube. 



Cypeeace^. — The Cyperacese are all anemophilous. The pollen 

 is at first spherical and subsides into a number of irregular forms. 

 The commonest is obtusely triangular. The pollen does not differ 

 much in size, nor do the pistils in length. 



Gramine^. —The Grasses are also anemophilous. The pollen is 

 at first spherical, and subsides into a 4-6 sided prism. There is a 

 single pore. 



The pollens differ greatly in size (figs. 17-19) in different species, 

 following roughly the lengths of the pistil, as already mentioned. 



