54 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



transformed axis itself; the carpels, or individual flowers, 

 are formed by repeated dichotomy of the primary floral axis. 



3. The envelope about the infloresence is the homologue 

 of the tubular bract below each node of the main axis. 



4. The male flower is also strictly terminal and arises 

 by the dichotomy of a primordium in the axil of the lower 

 of the two foliar leaves at each stem-node. The sister shoot 

 developed from the primordium becomes a lateral branch. 



5. The stamen corresponds closely in structure to the 

 ordinary angiospermous type. The pollen-spores are small, 

 with two nuclei at maturity; a conducting tissue is devel- 

 oped about the canal of the style, which nourishes the 

 pollen-tube. 



6. The ovule, like that of Naias, is the transformed apex 

 of the floral axis. 



7. The embryo-sac generally arises from the upper cell 

 of the sporogenous complex; its development is normally of 

 the ordinary type. 



8. The first divisions in the embryo correspond to those 

 in Naias jlexilis. 



9. Of the segments of the embryo cell, the terminal one 

 gives rise to both cotyledon and stem-apex; the second, 

 third, and fourth to the root, and the fifth to the root-cap; 

 a secondary suspensor of three or four cells is developed 

 from the lower segments. 



10. The development of the endosperm is essentially as 

 in Naias. 



11. Abnormal embryo-sacs much like those in Naias 

 were met with. 



12. The primary root of the embryo, as well as those of 

 the mature plant, have four distinct meristems ; i. e. , plerome, 

 periblem, dermatogen, and calyptrogen. 



Comparing Naias and Zannichellia, there are obviously 

 many points of structure in which they agree. The general 

 arrangement and development of the stem and leaves agree 

 closely in the two, and the arrangement of the tissues is very 

 similar. The origin of the flowers, too, as we have endeav- 

 ored to show, is essentially the same in the two genera, 



