20 



GENUS PALLAVICINIA 



of P. Levieri were much longer than those of either of the other specie? 

 that were studied, sometimes reaching a length of a centimeter or more 

 The archegonial receptacles are smaller than those of P. radiculosa, and 

 are more like those of P. Zollingeri. 



The Antheridium 

 Of the three species examined, P. radiculosa was the best for the 

 study of the young antheridium, as most of the stages of development 

 were found in the material. 



Fig. 10. Pallavicinia radiculosa. 



Early stages in the development of the antheridium. 

 Longitudinal sections. D, F, are cut in a plane at right angles to E, G. 



